I've stayed at both the FFI and the Residence Inn Maingate. The FFI has a very close location that makes walking very attractive. Do note that I believe they charge for parking now and do not comply with the brand standard to provide any breakfast. So breakfast is on-your-own. And it backs up to the I-5 so a significant portion of the rooms have exterior doors that face I-5 (I was lucky and "upgraded" to the other side facing the park).

This summer we stayed at the Residence Inn. It's an old-style eight-apartments per building RI but in a bit quieter location--well, except it is across the street from the fire station. We got upgraded to a "two bedroom" suite which had plenty of space to spread out and a full kitchen. It's a bit further walk but certainly doable if the kids are older or still in strollers. They do provide a reasonable if industrial breakfast (due to the high number of folks they have to serve).

When I booked this year's trip the costs were roughly the same once I included parking and I'd pick the RI over the FFI every time for the breakfast and space.

Saw the new Springhill which is probably an equivalent walk to the RI, but haven't stayed. Also saw the Courtyard under construction next to the FFI--I can only imagine the line at the Bistro 30 minutes before park opening!