How big? Enough for a couple little kids to run around or something?

They're a big rarer, but some of the full-service all-suites hotels have some bigger floorplans. I stayed in an all-suites Le Meridien in North Dallas that had huge suites. I've stayed in some Marriott Suites that had big suites. Both of those had a better floorplan than the typical ES, which is a little, dark, kinda useless room and a hallway to the bedroom. The Residence Inn and Homewood Suites two-bedroom versions might be okay for you - they'll have a living room with a window in it that is of a decent size. This is a case where you might actually prefer the oldest properties in those brands: especially with RI, the earlier builds had some BIG two-bedroom, two-story suites. (Whether the property has been well maintained will vary.)

If none of those work, then I'd look at VRBO, Booking.com, or Airbnb.