My favorite two places in downtown Indy are 14 West and the Oceanaire. If you have a car, drive to Oakley's Bistro on the north side of town, the best place I've eaten in Indiana. You can read detailed reports of my meals at these and other places in Indianapolis in the topic at www.chowhound.com/topics/348586
I do enjoy the fresh oysters and crabcakes at Oceanaire. Unfortunately, my friends and I have found any fresh fish to be overcooked MOST of the time. Not quite sure about 14 West??? Are they going under again. I've been to Oakley's Bistro once and it was alright. I'm sure it seems great for all of those diners who like CONfusion!
It always depends what you are in the mood for. If the same ol'-same ol' chain stuff is fine then downtown indy has plenty of that. I would definitely reccommend Massachusettes Avenue for good food. From the IUPUI campus just take New York Street all the way to a three street intersection with Mass Ave. and Delaware St. Go along the Avenue and you'll find Bazbeaux Pizza, McNivens Scottish Pub, Elements (seasonal menu changes daily), Old Point Taven (Bar food), the Rathskellar (German), Aesops Table (Agean/Greek/Med.), Yats (Cajun), the Chatam Tap Pub, and at the very end of the Avenue beyond College is R Bistro (seasonal menu changes every week). Elements and R Bistro are your most serious food choices in all of downtown but any other place is good for what they offer. WARNING: JUST STAY AWAY FROM AGIO (EXTREMELY OVERRATED AND PRETENTIOUS). Barcelona Tapas is one block south on Delaware St. beside India Garden (don't get the buffet). Good luck and I hope you enjoy your stay.
I actually like Adobo Grill (http://www.adobogrill.com/) better than El Torito, which struck me as an expensive Chi-Chi's. Although if nicolea76 doesn't have a rental car, both options are out of the question because they're both on the northside!
IUPUI is kind of a dining black hole. It has lots of semi-fast-food chain options (Noodles and Co, QDoba, Quiznos) and some stuffy, overpriced fare (Chancellor's, Bugg's Temple). I've heard University Place Hotel has a place called the "Den" that has good beer and decent bar food but I can't vouch for it.
Good lunch spots downtown(ish) are:
Hoaglin to Go
Downtown is rife with chains (Bertolini's, Champps, Rock Bottom, Claddagh, McCormick & Schmick) and steakhouses (Mo's, Morton's) though.