300 is the closest loop to the dog park and is a pretty easy walk to the Settlement area (restaurants, boat launch, gift shop), but also not too bad of a walk to the Meadows (pool, another gift shop, a seasonal snack bar, Bike Barn) area either. Of course the busses are a fine way to get around and without bikes you'll want to use them to get to the Outpost to grab a connecting bus to the parks or DTD.
The hierarchy at the Fort for sites with full hook ups goes like this:
Full Hook Up
Preferred
Premium
(there is also the Partial hook ups, but they are not pet loops)
Here are what those classifications are as far as loops go:
100 - Preferred
200 - Preferred
300 - Preferred Pet
400 - Premium Pet
500 - Premium Pet
600 - Premium Pet
700 - Premium Pet
800 - Premium Pet
900 - Premium Pet
1000 - Premium
1100 - Premium
1200 - Premium
1300 - Premium
1400 - Premium
1500 - Partial Hook-up
1600 - Full Hook-up Pet
1700 - Full Hook-up Pet
1800 - Full Hook-up Pet
1900 - Full Hook-up Pet
2000 - Partial Hook-up
So "worth it" is kind of in the eye of the beholder. Different people prefer different classifications for different reasons. And different people prefer different locations for different reasons. And really, I don't think there's a bad site in the whole place

But you won't find a loop that is close to EVERYTHING since the different amenities are spread out.
We are really big fans of biking around the Fort, I know you said "probably no bikes" but they sure are nice to have for getting around.