Car-less in St. Paul.....
Definitely go to Tanpopo - the food is delicious and the menu is pseudo-vegetarian (with one pork dish). It's near the site of the St. Paul Farmer's Market, which is worth a visit if you're here on the weekend.
You're also close the new Pop! in downtown St. Paul. I haven't been there, but I like the original Mpls location - they have a tasty walleye sandwich. (Though I'm not sure if the St. Paul place has the same menu.)
I've seen an Crowne Plaza shuttle van on West 7th, so I'm guessing you could somewhere further with advance planning. If so, I'd suggest Ngon on University Ave., about 2 miles away. You'll have to order carefully to avoid the meat, but there are a number of fish-based and vegetarian dishes. Everything I've tried there has been delicious.
Have a good stay!
How do you feel about the bus? quick bus ride to Grand Ave opens up a few more options.
Everest on Grand, Cafe Latte, Punch Pizza, Coffee News Cafe all good for meat free.
Mertiage has wording on their menu about veggie friendly no problem (i think) and last time I was there I was inquiring about the soup and the waiter was quick to mention it was vegan. So they "get it"
Enjoy the visit!