We've gone with every combo imaginable, and these are some of the actual restaurants in the park where we feel like we don't have to leave the park and still get "park food".
Rancho Zocolo serves large portions. I personally like the cheese enchiladas. We typically will share a drink and share the enchiladas. You get rice and beans with it.
I ditto the chicken fusilli pasta at Pizza Port in tomorrowland. The serving is huge, more than enough to share with two people, I think. And, I've found their kids pasta meals (though not their kids' pizza meals) to be VERY generous servings. They do spaghetti with (or without) sauce and a huge meatball. Fills up even my 12 year old.
The chicken dinner at the Plaza is huge! Typically more than enough for two adults to split.
The corn dog cart on the end of main street has corn dog combo meals for around $6. That's usually a good deal, and you can grab it and sit and watch the parade.
On more than one occasion I've ordered kids' meals for both my younger two and myself. Especially at Taste Pilot's Grill in DCA. Their kids meal has two sliders and that's more than enough for me. You can typically get the PB&J uncrustable or chicken nuggets just about anywhere. I've done the pasta at PP, too. Unless I'm starving, that it typically more than enough for me. That way you get drinks, including milk if you want it, and sides. And, you can request french fries instead of fruit for some or all if you want.
Another idea, and it may sound counter intuitive, but I've found that often this will save us money overall during the day, and that's to do a big character meal for late brunch. I really liked Lilo's, and it has a wide variety of items, but not quite as expensive as Goofy's. Or Minnie's is good, too. Plus, kids under 2 eat free, so you wouldn't have to buy anything at all or worry about getting something yourself for your little one. We go for the latest available time. But, the reason I've found that to be good is that we don't each much before we go to "breakfast", maybe a granola bar or something, and then we eat alot at lunch, and then we're not all that hungry for the rest of the day. Last time we did that, DD and I split a kids meal for dinner. We just weren't all that hungry. Another time, we ate character meal for brunch, and then didn't eat dinner until after the park closed and stopped and got something at McDonalds.
We have brought entire meals in. We've also brought sandwiches only and gotten fries and onion rings, etc. I almost always bring soda, as I'm a Mt. Dew fiend, and they only sell coke products. I try to always bring water, even if I've puchased it at one of the hotel gift shops, as it's cheaper than buying it in the park. We bring kool aid singles, too, for when we're sick of plain water. When we spend the night, I typically bring cereal and milk and we eat before we go. Just FYI, you can pack a cooler as your checked item and fill it with dry foods/snacks, juice boxes and water, etc. Just not ice. We've done that a number of times and seal it with tape. The last couple of times they've unsealed it and resealed it with their own tape, so they will look into on occasion, but never had any troubles. Plus, things tend to get less broken as the outside of a cooler is pretty hard sided. To keep things from sliding, I typically pack a beach towel in the top. I don't use clothes in case there's a problem with any sort of leakage.
Also, IHOP right accross the street from DLR entrance has kids eat free every night. That has saved us some money. Mimmi's has huge portions and more than enough to share with another adult, or if you and your older child want to share something.
And, you can order from Albertsons and they'll deliver it directly to the hotel. Just go to albertsons.com.
And, finally, I think your hotel is going to be a bit of a hike down Harbor for you. Not undoable, but a bit of a hike or a trip on ART or their own shuttle (not sure which one that is for them), so going back to the hotel for lunch on a regular basis may be a challenge.