We stayed at Hotel Max for one night during a heat wave in 2009 that had the outdoors temperatures in Seattle almost unbearable at 11PM at night. Our room had the lovely view of the space needle you see above and was very nicely furnished. The rooms are small, but if you're staying right in the middle of downtown Seattle I would hope you don't plan to spend much time in your room anyway! The staff were very friendly and the overall decor of the place was kind of neat to look it, very artsy. Hotel Max was very centrally located which made it easy for us to walk down to Pike Place Market and explore.
Pensione Nichols is one of the neatest places I've ever stayed and would very much recommend to anyone who wants to spend some time in downtown Seattle. It's in a great location with a beautiful view of the harbor (see picture above) and it's got such fun charm to it. We stayed in one of the guest rooms which shared a common bathroom, but they also have a small apartment with it's own kitchen which would be perfect for cooking your own gluten free meals!
We stayed at Pensione Nichols before my gluten free days, so I can't write much about how well they could accommodate those needs for breakfast. However, I can say that the breakfast they did provide was by far the best I've ever had at a B&B. Yogurt, fresh fruit, granola, baked goodies, and at the table french pressed coffee. Yum.
The Sheraton is my dependable hotel in downtown Seattle, I've even stayed there when something was wonky with our first Seattle house. There rooms are very spacious and clean, have fun views, and I've even been able to order a gluten free dinner from room service. So it's a good place to land and it's easy walking distance from all the great downtown Seattle attractions.