Consumer discretionary is one of the more diverse subsectors in the market because it includes a variety of companies ranging from restaurants and specialty retailers to media conglomerates and automakers. As the name "consumer discretionary" implies, these businesses sell goods or services that are nice to have but that people don't necessarily need. Therefore, these stocks tend to perform better when the economy is doing well, since consumers have more disposable income during such periods.

With a steady economic recovery now underway, here are two consumer discretionary stocks worth watching.

A latte to love
When it comes to where to spend disposable income, Starbucks (NASDAQ:SBUX) is a favorite among soccer moms, college students, and businesspeople, and even kids, thanks to its mini Frappuccinos and snack offerings. The java giant is firing on all cylinders lately. However, the recent expansion of Starbucks' Mobile Order & Pay platform is perhaps the most compelling reason for investors to watch the stock today. The specialty coffee retailer expanded its mobile pay platform in March to more than 650 Starbucks locations throughout the Pacific Northwest and in mid-June announced a rollout to 17 more states in the south and central U.S. Customers can use their smartphones to place orders for pick-up (and to pay) at more than 4,000 Starbucks stores throughout the United States, and the company plans to bring more locations online in the quarters ahead.

Source: Starbucks.

The caffeinated retailer already had one of the best digital offerings of any U.S. brick-and-mortar retailer with its My Starbucks Rewards program, which enables customers to pay in stores using their smartphones. In fact, even before the rollout of its new mobile ordering platform Starbucks was seeing over 7 million mobile transactions in its stores each week.

Nonetheless, its new Mobile Order & Pay system has the potential to boost the amount customers spend per order, increase order frequency from existing customers, and reduce in-store wait times. Whether you own shares of Starbucks or not, this is certainly a development worth watching.

An action-packed growth stock
Shares of mountable-camera maker GoPro (NASDAQ:GPRO) look a bit pricey today trading around 74 times earnings and with a price-to-earnings growth ratio of 2.54 -- one of the highest in the industry. However, the company's plans to grow its content business, enter the burgeoning virtual reality market, and corner the live sports arena make it a stock worth watching.

GoPro is in the early stages of testing how to better monetize its user-generated content. The company's content-driven business model has earned the company a reputation for having some of the most viewed content on the Internet. In fact, GoPro's YouTube subscribers are up 48% year-over-year to nearly 3 million, followed by 1.4 million Twitter followers and an awe-inspiring 4.5 million followers on Instagram, putting it among the top 10 brands there.

Source: GoPro. 

While GoPro is currently focused on providing consumers better tools to capture and share video content, the company could derive revenue from this media down the road through licensing deals and ad-based revenue from its GoPro network. And this is only one piece of GoPro's promising growth story. The company's recent acquisition of Kolor, a French virtual reality and spherical media solutions company, gives GoPro a foot into the budding virtual reality market. GoPro said it would release a six-camera spherical array accessory for capturing spherical or virtual reality content later this year.

In addition to monetizing content and entering the VR market, GoPro also teamed up with Vislink earlier this year to enable live broadcast capabilities within GoPro's HERO4 cameras. The company has already used this technology in partnerships with both the National Hockey League and ESPN to broadcast live sporting events to great fanfare. This creates yet another way for GoPro to diversify its revenue stream while also evolving from a camera maker into a media and content company.

Bottom line: Some of the best growth stocks of the last decade were once hidden behind sky-high valuations and largely untried business models much like GoPro. For these reasons, I believe GoPro is worth watching despite the stock's expensive valuation today.

Going for growth
There are dozens of interesting stocks within the consumer discretionary space. However, Starbucks and GoPro are worthy of investor attention today because of their outsized growth prospects and easy-to-understand business models.