Here's a summary, in case my transfer to long term memory fails because I'm ill.
I'd _love_ to stay on site. I really would. We could leave one car seat at home, skip renting a car, let Disney's Magic Express (DME) pick up our luggage for us and deliver it to our room, use vouchers for our meals, blah, blah, blah. Here are the issues:
(1) Dietary: the problems here are legion, and mostly mine. Solving them typically involves getting a kitchen and groceries. Both are possible on-site, but not necessarily cheap, nor is there any guarantee that if I use the grocery delivery service I can reliably solve my collection of issues (_any_ of the grocery delivery services). Of course, there are taxis. The other issue is getting a kitchen in reasonable proximity to the Magic Kingdom (MK) which is where we anticipate spending most of our time. I'm also kinda leary of the whole bus thing, which makes places like the Contemporary/Polynesian/Grand Floridian a lot more tempting (monorail instead of bus to MK) BUT none of those have kitchens, and they are really not cheap. The best option for solving the dietary issue is probably one of the Fort Wilderness Cabins (close to MK, bus or boat), which are available, unlike the Villas at Wilderness Lodge, which are often not available.
(2) Transportation: see commentary in (1), but in general, there's a big time cost to going back to the room for a nap at virtually any lodging option, on or off site. The exceptions are the Contemporary/Polynesian/Grand Floridian noted above, being on the monorail. Because we'll _only_ go during Value Season (aka Not So Fucking Crowded) and during reasonable weather (a subset of Value Season, that is to say, not any time between mid-Feb and sometime in September), it may be possible to assume we can skip the parking tram by parking close enough to TTC to just pick up the monorail. Here's hoping. Post nap that's probably a little iffy (and raises a fascinating question about whether parking at MK involves in-n-out privileges or I'll be paying $22/day instead of $11).
(3) Sleep: basically, we _have_ to have two sleeping spaces with a closable door between them. I cannot wear earplugs with an under one year old and I cannot sleep in a room with R. without ear plugs currently. Also, R. doesn't get much sleep with the frequent middle-of-the-night nursing noises likely to occur with an under on year old. The good-transport/bad dietary options are bad-sleep options as well (really expensive); Fort Wilderness cabins are the likely compromise, unless we become magically able to book a Villa at Wilderness Lodge, which isn't exactly cheap either.
We have really good solutions for most of these problems: rent a car at the airport, drive it to an off-site hotel with a 1 bedroom (or more) suite with a full kitchen. Send R. off to a grocery store at some point. Eat the breakfast at the hotel part of the time and eat in the room for some meals. Return to the hotel room for naps most/all days. And we can do all of it for considerably less than most of the on-site options (altho again, the cabins are kinda competitive). No dining plan, of course, but that's no big deal; there's a lot of question about how much that thing really saves anyway.
I've got a staggered list of hotels that satisfy the criteria, from the ultra-cheap and somewhat suspicious Enclave Suites (this property appears to change names every couple of years) to the branded and familiar Residence Inn to the Caribe whatever, which is highly recommended by all the Disney fan sites.
Research at this point would probably be oriented to answering minor questions (in-n-out privileges parking? ETA: Yes! Pay once per day. Get a slight discount on MYW tickets by buying them through AAA and they'll give you a AAA Diamond Preferred Parking voucher which lets you park possibly closer to the entrance of the 4 major parks), nailing down a list of have-to/want-to/kinda-nice attractions, figuring out if we want to go to Islands of Adventure, putting together a list of sit-down-meals for setting up ADRs (reservations in disneyspeak). I can't nail down dates yet, because while A. kicks me a lot and has made her presence known in other ways, I don't know a thing about her personality and therefore whether it would be a disaster to bring her anywhere. The earliest I'd consider going would be the first part of December; more likely we'd shoot for Jan/Feb. If we miss February, plans would be off until September, and at that point, I'd be monitoring the opening of the Harry Potter park and contemplating whether A. is likely to go on some kind of nursing/potty/whatever (this happened when T. was 10 months and we traveled) strike and therefore I should continue to delay.
If you'd like to meet us down in Orlando and meet the mouse together, we'd be happy to connect our plans (subject to that insane list of criteria above) -- otherwise, watch this space for developments.