Agree with the how you will use it assessment. We just returned from our first extended trip with our Lance 1685 - a 20'9" t/t with a slide. Lots of room, some don't like the sideways bed, but it doesn't bother us to save the extra 3' - the next size up with the walk-around queen bed is an extra 3'.
We discovered we like camping outside of national parks, BLM, forest service etc. We like less people, less "rules" -- when we can & can't use the generator for example, no one around to bother. Having never had dogs, not sure, but there might be less restrictions on dogs in BLM/forest service campsites? But the travel trailer might need to be different as well as the tow vehicle.
We love our trailer - we lucked out when picking the trailer ... the tow vehicle may need to be re-evaluated. We discovered we really like exploring dirt roads - not quite 4X4, but definitely beyond Tahoe/Suburban capabilities, or that's what we were told. We have a 4 Runner and had planned to buy a Tahoe ... until we talked to some people that were unhappy with their Tahoes due to wheel base and ground clearance for some southern Utah dirt roads.
Just a few considerations outside the usual. Good luck & ENJOY!