What's good about your competitors' products or services? What could use improvement or be replaced with something better? What's your unique competitive advantage? To find out, read reviews on Amazon or Yelp or look for tweets and Facebook posts about the competition.
Want to learn about your competition's weaknesses? Use a SWOT analysis. The W stands for weaknesses! You can find SWOT analyses for most major companies by searching Business Source Complete for "(company name) AND SWOT".
Are there a lot of similar companies in this area (competitors)? How much do the competitors earn in revenue? How much do they spend on rent and payroll? Use the U.S. Businesses database within ReferenceUSA to locate and analyze your competitors.
Patent searching can be a little complex, because patents use very stylized language, and because they are often filed in particular nations (e.g. all US patents are filed with and disseminated by the US Patent and Trademark Office, while Japanese patents are filed and disseminated by a similar organization in Japan) but several tools can help you find them more efficiently.
Considering Boulder for your venture? The Boulder Economic Council has lots of facts about doing business in Boulder.
How much of your time and capital will be tied up in finding, creating, and receiving your products or materials? Can you outsource? How easy would it be to replicate your product?