Baltimore Aquarium tickets are expensive but well worth the money. I'm not really sure about availability of discount coupons though as my parents have been members for years and my sister volunteers there so we usually go on their free tickets.
Get there as early as you can as it can get very crowded - although it might not be quite as bad now that school is out for the summer and there shouldn't be any school groups there.
Make sure to get your tickets for the dolphin show (they are free with admission but you do have to get the ticket on the way in and they are for specific times). You should also try to plan and watch the divers feed the sting rays and turtle - feeding times will be posted (I think it's around 11 a.m. and 3 p.m. but I'm not completely sure).
You will NOT be able to bring a stroller into the aquarium as there is very limited space there. There is a stroller check area on-site though if you need to use a stroller for transportation to and from the aquarium. They used to have backpack carriers available (for free I think) but I'm not sure if they still do that.
As far as seafood is concerned - my husband says that there is a Phillips Seafood restaurant on the harbor that he thinks isn't too terribly expensive. Here's a link to their website (you can download their menus):
Phillips Seafood .
Unfortunately, most of the restaurants in the Inner Harbor aren't cheap. Within walking distance of the aquarium there is an ESPN Zone, Cheesecake Factory, and Hard Rock Cafe among others. Here's a website with a listing of restaurants in the Inner Harbor that you also might find helpful:
Click Here.
If you're looking for another place to visit while you're here both
Port Discoveryand the
Maryland Science Center are a couple blocks away. Maryland Science Center tickets aren't cheap either, but my boys had a blast there (they are 2 and 4) and there are actually a ton of child friendly things to do as well as an I-Max theater. Port Discovery is geared for children, but neither my husband or I were very impressed when we went. Tickets are cheaper than the Maryland Science Center though. There are also a couple ships on the water around the aquarium that you can buy tickets for and "tour" but we've never done that so I'm not sure if it's worth it or not.
One more thing, plan to pay $15-$20 to park for the day in one of the garages or parking lots. Parking in the Inner Harbor (along with everything else) is NOT cheap. You can park on the street if you don't mind going to feed the meter every couple hours, but it will probably be easier just to find a garage. There are a few garages that are a little cheaper - we found one close to the Maryland Science Center (it's small though) that was less than $15 I think.
That's all I can think of right now. Let me know if you have any specific questions and I'll try to answer them although, ironically, we're leaving tomorrow for Pennsylvania and won't be back until Thursday

. Like I said, my sister does volunteer for the aquarium so if you have any specific questions, I might be able to get an answer from her. Hope you enjoy your trip!