Well - To clear a few things up -
Broad St. is not really near the university district, unless you are talking about a different University than Ohio St. (i.e. Capitol or Columbus St. or the West Side Beauty School) - And depending on which side (east or west) Broad st. might not be an area you want to be driving around -
North High Street is the place to be - It goes from downtown, to the trendy short north, to the campus district, up to lesbian friendly Clintonville, then on to Old Worthington and finally out through the suburbs up to Detroit. N. High Street, in the Clintonville area, is also home to my favorite vegetarian hole in the wall from childhood - Whole World Bakery -
Whole World Bakery - Although the very small wait staff can be a bit rude sometimes, and you can only fit about 15 people in the place before you start tripping, you will undoubtedly love the atmosphere and food. Especially the breads (at least that's what I remember liking the most). Beware, though, if you order the whole wheat pizza, be prepared to wait 45 minutes for it =/ --- Oh, its strictly vegetarian too - but good and homey -
http://search.cityguide.aol.com/columbus/restaurants/whole-world-natural-restaurant-and-bakery/v-105237242
Also, just off N. High Street in the short north is Benevolence. People seem to enjoy this one more than most -
http://www.benevolencecafe.com/
Again on N. High St - The Blue Nile Ethiopian Restaurant - This is not strictly vegetarian, but as you might be aware, Ethiopians don't have meat at the top of their food preferences. Good restaurant - a bit close to the U District though.
Another one, just up the street from Blue Nile - Alana's - check out the menu - very vegetarian friendly - don't worry, when you look at the menu it looks like it's a lot of meat - But believe me, just ask, and you can get great veg food.
http://www.iwaynet.net/~birdseed/menus.html
Check out the North Market near Benevolence - North Market will offer everything for vegetarians or carnivores. In fact, the whole Short North region will cater to vegetarians without blinking an eye. They'll get you what you need =)
As far as I-71 area - not too great - unless you want to check out the nation's second largest population of Somali immigrants - They still haven't built too many restaurants, but if you hang out at the Tim Horton's in the morning, you can chat =)
Easton - ugh - yeah its big and there is food - But seriously you could get down to the short north in as much time as it would take to go to easton and park and crap like that - And its a very unfulfilled feeling- Don't think you have to take the freeway, just take morse rd over to high street and drive down. Takes about 20 minutes total if it isn't rush hour -
Anyway - Search the internet a bit - People tend to overlook Columbus, but one of its really nice attributes is the quality and diversity of food you can find there. You will have to look though! It's not always apparent.
And cameron mitchell restaurants dot the city, but don't really offer anything but decent food - I think you can probably find that elsewhere and also get some "flavor" =)