That's true! Honestly, the younger she is the more important to me that we're at Contemporary when we go, which doesn't help the "smaller, inexpensive" idea, but maybe a long weekend at first and then back for a full week in a couple years. Walking back to the hotel for a nap or as a break will be KEY.
Is that because you can ride the monorail to the parks? Because that is a BORING resort for a 4YO. My kids were not even impressed that the monorail goes through it. We stayed at Pop Century and they loved walking all around and looking at the amazing stuff and taking pictures with the "GIANT TOYS". The time spent in parks outweighs the time in the room. Plus, you have to take the monorail to the ticket center/transportation center and then get off to get to Epcot- the monorail does not run directly to there, or just take a bus.
For us, we would rather do more budget trips than 1 large expensive trip every 5 years. My almost 3 year old has barely any memory of the trip we took last year so you may find that the memories you look for are mainly for you and your husband, and then you want to go back in a year or two.
As a mom of 3, I would look for kid-themed resorts over the contemporary, mainly because as a kid, they will love the goofy themed rooms so much more than the "stylish" ones. I showed my kids the pirate room at the Caribbean, and they still wanted Pop Century.
My husband and his family stayed at the Swan and Dolphin as kids and he said he barely remembers it because it was just a normal fancy hotel to him. (That was before POP).
Honestly, if we still fit into a POP room, that is where we would stay, but we will be camping this time because the AOA is a bit out of our "Return to Disney every 18 months" budget.
I wish we would have taken our firstborn earlier, but we kept having another every 2 years

and we could not afford it then, so she was 6 when she first went and loved it, but the 2YO and 4YO loved it too.
If you decide to wait- just plan a little at a time, and there is no reason not to make a countdown timer anyway
