Before hiring any contractor, be sure to do some research and get quotes from a few contractors. At a minimum, check the BBB and make sure each of the contractors you get a quote from is licensed in your area. If you are in Denver, you can check for their contractors license at Denvergov.org
Some companies will offer bathroom design, expert plumbers, and artisans for your tile work and lighting. Others companies focus on getting a job done quickly and efficiently. Either way you go, if you are planning on a glass shower door or custom mirror make sure to include the glass company before tile gets put in. Once you have found some contractors you like, get at least 3 quotes for your project.
The quotes you get will typically be a contract waiting for your signature. You should review the contract fully to be sure it protects you. A good contract will detail the work to be performed, estimate start and finish dates, define a pay schedule, protect you against liens from subcontractors, and state whether permits will be pulled. If designing the bathroom is part of the quote, ask for it to include an elevation drawing and a layout drawing. Avoid contractors who ask for full payment up front and contractors that expect you to be the one pulling the permits.