SAN FRANCISCO -- To mark the Cinco de Mayo holiday this year, Domino's Pizza festooned its Facebook page with a string of posts, including an image of a Mexican-themed guacamole pizza that garnered over 2,000 "likes". But visitors to Domino's companion Google+ page on that day found less festive fare: The most recent post was from October 2012.
Two years after introducing its social network, Google Inc. is struggling to win over the brands and businesses that have been its most loyal customers in the Internet search market.
For Google+ to thrive, it is vital to draw in household names, not just to lay the groundwork for potential future business, but also because users of the site have come to expect being able to follow, comment on or even vent about their favorite brands.
Progress has been slow. Rival services from Twitter to Amazon.com Inc. are increasingly competitive in vying for corporate attention and marketing budgets, while technical shortcomings of Google+ have put off some companies accustomed to the flexibility of Facebook, marketing and corporate executives say.
The biggest problem for Google+ is that many more consumers use Twitter and Facebook - and they log in to Facebook for much longer periods.
A Google spokeswoman said Google+ has been used by millions of brands and businesses, and that the benefit of the service extends beyond Google+ web pages, by providing brands with social capabilities that enhance Google's other products.
Google+, which was first introduced in June 2011, has roughly 135 million users that it says actively use its website news stream, and about 500 million that have set up Google+ accounts at some point, according to the company. Still, Facebook has 1.1 billion users who engage with the service at least once a month, while Twitter has 200 million.
The average U.S. visitor to Google+ spent 6 minutes 47 seconds on the site in March, versus more than 6 hours on Facebook.com, according to Nielsen Media Research, though the data does not include activity on the social networks' mobile apps.
"The main reason we are more active on Facebook than Google+ is because that is where our customers and our target demographic are spending their time," said Dave Gilboa, the co-founder of online eyewear company Warby Parker.
Many businesses do build outposts on Google+, eager to benefit from its integration with Google's popular Internet search service. Some corporations have even used its online video feature for splashy product launches.
But the flurry of commercial activity common on other social networks - from restaurant promotions to movie trailers - is harder to spot on Google+, raising questions about its ability to rival Facebook or Twitter as a thriving online community.
Google does not provide detailed information on user activity. But the level of consumer engagement on other social services, such as Facebook, Twitter and Pinterest, is "orders of magnitude higher" than on Google+, Gilboa says.
Still, he noted that a key benefit of Google+ for Warby Parker is the way it adds social capabilities to other Google services, such as YouTube videos his company produces.
An informal survey by Reuters showed that of the 100 most valuable global brands in 2012 ranked by Millward Brown, a media research firm owned by ad giant WPP, 72 have a presence on Google+, compared with 87 on Facebook.
However, roughly 40 percent of the brands with pages on Google+ have either never posted any content, or do so infrequently. Seventeen brands, including Nike and Pepsi, had not posted to their Google+ page in more than a week.
The McDonald's Google+ page did not have a single posting. A spokeswoman for the fast-food chain said only that the company was "not active" on Google+.
"In my personal network, I have very few people who are actively using Google+," said Dan Nguyen-Tan, vice president of sales and marketing for San Francisco-based bicycle company Public Bikes, which does regular promotions on Facebook but has not created a Google+ page. "That could be a reason why I haven't thought about it as an effective tool."
Some also complain that Google+ is too restrictive a canvas.
Its profile pages are more limited than on Facebook or Twitter because they don't support iFrame, a Web standard that allows multiple Web pages to be embedded within a main page.
"I don't think that Google+ has enough creative options for brands to be able to marshal a lot of resources and activity around it," said Vince Broady, the Chief Executive of Thismoment, which develops social marketing campaigns and Web pages for brands such as Coca Cola and Intel.
Gretchen Howard, Google's director of global social solutions, said the company was working its way down a "wish list" of features that businesses have been asking for.
Over the past year, it has rolled out a tool that allows software developers to connect with a brand's page, though that has so far been offered only to a limited group of partners.
That's not to say Google+ hasn't had its share of success stories.
Howard points to examples such as automaker Fiat's launch of its new Panda car using "Hangout" video conferencing, and the 40,000-member baking community page created by chocolate company Cadbury. According to Google, more than 100 brands on its social network have amassed more than 1 million followers.
And Google's search engine, the most popular in the world, is a big draw. Businesses who have registered with Google+ often get extra visibility in search results, with a portion of the results page displaying information from their Google+ profile.
Search ads that incorporate Google+ information - such as the number of users who follow a brand - have a 5 to 10 percent better click-through rate than regular search ads, said Howard.
"Right now, the value isn't in the network itself, it's in what it can do for the search results," said Greg Finn, director of marketing at search engine optimization firm Cypress North.
Google has never articulated how, or even if, it intends to make money off its social network. But analysts say the goal is to prevent migration of Internet users to Facebook and other social networks, while improving its core search advertising business and possibly providing a new source of income.
While Google+ does not feature any ads now, Pivotal Research Group analyst Brian Wieser said attracting major brands could be the first step to an important, high-margin revenue source.
New ad space inside Google-owned websites is particularly valuable because it doesn't need to share revenue, as Google must do when its network places ads on other websites.
"If you're Google, you really want to have more owned and operated properties," said Wieser. "That's a wonderful, high-margin piece of inventory."
Google+ is a means to that end, he said.