We do it the "old fashioned" way by scrolling around Google Maps. It's our primary navigation tool anyway, so it's handy if I find something marked on the map I can just click on it and hit "get directions" and it'll take me there.
Granted, the navigation is not RV specific, so I do have to be careful, but being able to scroll around the map of a specific area, find something I'm interested in, then just click it to find out more, I think it's pretty darn handy. Most often I'll just click the "satellite" layer on and see what I can see for parking/access.
Every now and again, I'll punch it into my Garmin (which IS set up for my RV) just for backup, but the original research of the destination almost always comes from Google.
And it's free.
ETA: I'll often have a "primary objective" with at least 2 or 3 "alternates". No matter what you're using, sometimes you don't know what's really there until you have "boots on the ground". If I pull up to my primary and something's off, I've already planned at least one alternate.