I was in Cleveland recently for a training class at ASM International... checked out the Zoo it's it's pretty good, a lot of the buildings are older but the display's are well maintained. Orangutan exhibit over in the rainforest area was VERY good & the Lion area is right next to the food court.
I was impressed with the Science Center (easy walk from the Hall of Fame) it's very well done & has an IMAX that projects up onto the ceiling for a surround / immersion effect.
If you go to the R&RHOF (worth seeing once IMHO) DO NOT use MapQuest for directions, 1st time I was in Cleveland I used them& it routed me though the absolute worst neighborhoods possible. Drug deals, prostitutes working the corner... you name it we saw it on that drive, including one guy showing off his gun when we didn't want to buy some crack.
Foodwise, they have some good choices. One place inparticular stood out, a little hole in the wall diner type place called Your's Truly Retaurant on Chagrin Blvd. Great fresh food with some suprising items on the menu... if you're familiar with the Food Network this is the kind of place Guy Fietti(sp) should visit on the show "Diners, Drive-Thru's & Dives"