Allstays, backed up with RVparkreviews for us when we're on the road. On travel days, we don't know just how far we're going to go until the afternoon, so don't look for park options until then.
As for what we're looking for... For over-night stays, we go by the description on Allstays and feedback/reviews on RVparkreviews, looking for a location that isn't to far off of our route, preferably pull-thru's for easy in/out, and to some extent, price. Amenities don't matter that much to us as we're there for just an evening. We never stay at a place that is less than 3 stars on a 5 star scale based on reviews, and target 4/5 star parks when available at a decent price.
For extended stays, we look for the quality and size of the sites, including things like wooded settings and privacy. If longer than a week or so, full hook ups are required. Price is also a factor, of course, but we are fortunate enough that we can afford to pay top dollar if the park and site quality warrants it. Amenities are factored in as minor benefits for us as we don't require campground showers, bathrooms, or laundry facilities. A pool is a nice-to-have in warm climates, but lack of one is not a deal-breaker.
Note that we are a retired couple that spends around 6 months of the year traveling around the country. No kids, furry or otherwise, so dog parks, playground facilities, etc, are not factors for us.
Hope this helps...
2008 Jayco Designer 35RLSA pulled by a 2007 Chevy 3500 D/A SRW
