To summarize some of the stuff above and my experience.
Before starting - realize that most organizations will sign up almost any RV park for membership. The quality/ amenities/ features are going to vary greatly. Not only are our individual definitions of 'quality' different, so are the definitions of the various organizations.
Only groups like the US Federal government or Thousand Trails actually own the campgrounds/ RV parks. Even then the 'quality' and features vary tremendously between different locations.
1) The absolutely most important single option is a US Federal Senior Pass if you, or the spouse if over age 62. You won't get 1/2 price camping at all US Federal campgrounds. There is a tendancy to contract out campgrounds with electrical hookups. On those you might get 30-35% cheaper rates (you get 1/2 off the base/ dry camping rate, but have to pay the full utility fee).
2) Clubs aren't memberships in the camping sense. Belonging to Good Sam, Escapees, etc is about the group and the benefits of belonging to the group. Getting a discount on camping is a side benefit. Not a primary reason to join. Most places that offer discounts for those and similar groups also offer discounts for AAA, or AARP. It takes a lot of detailed work to pay for your yearly membership with campground savings at 10%. If you have a motorhome - most strongly recommend you seriously look at FMCA - Family Motor Coach Association - it is the only group owned by the members. Good Sam is owned by the company which owns Camping World. Escapees is owned by a family. Both are very good - but both are for profit businesses.
3) Deep discount programs like Passport America - do pay for themselves in savings quickly - IF YOU USE THEM. PPA and simlar deep discounters (40-50% off camping) are not for long term stays. They are for when you are traveling distances and looking for a cheap(er) place to stay. Sometimes their associated parks are in the right locations, some times they are not. Just 10 days ago, I drove past a Passport America Park with a rate of $20 per night to stay at another park with a rate of $35 per night. Why - because it was 200 miles down the road, and I was making very good time that day. Tonight, I'm at my first night of four nights at a PPA park. While the PPA rate of $19.50 per night is good (+ 10.45% tax) - I could have got the same spot for $26.50 with Good Sam, $25.25 with Escapee's. Yes, I've stayed at some which only honor PPA, and some which honor everything.
4) Free 'camping' - Walmart has a national policy to allow RVs to overnight in their parking lots. Most truck stop companies also allow RVs to overnight. Some other companies do also. (All of these can be stopped from allowing RVs by local city ordinances.) Some general rules. This is a overnight only stop. Don't put out slideouts unless they overhang the curb, or you can block them with a tow vehicle/ toad.
5) Membership Camping - in the RV sense this usually refers to a group which either owns a series of campgrounds - Thousand Trails, Ocean Canyon Properites, Colorado River Adventures. There is a cost for the membership which can be quite high. Again the key is that you need to use the membership full to get a benefit. Most are not about saving money on camping, they are about having access at a set lower than the public cost to the facilities. They can be used to greatly lower total yearly camping costs - if you use the membership facilities extensively. Many 'Resort' camping companies/ facilities also sell memberships - these are very much like timeshares.
6) Reciprocal Membership Programs - Coast2Coast, RPI, AOR - these have a key provision that your must belong to a resort in their group (i.e. a Membership), and you get privileges for reduced rate camping at other resorts that belong to that program/ group. Some 'home' memberships can be relatively cheap - $180 per year or so. Some can be quite high - $4-8,000 annually.
We are full-timers. We travel when and where we wish, and we belong to several programs.
We are both over age 62, have US Senior Passes - and enjoy staying at Corps of Engineers parks when available. We just spent seven nights dry camping in National Parks in Utah at 1/2 price.
We are Good Sam Life Members because we enjoy our home Good Sam group, enjoy Good Sam state rally's, and occasionally stay at an RV park with a Good Sam discount. Once or twice a year.
We are Escapees because we use their home bases as our residence / domicile, their mail service, support their advocacy for RVers. I think I've stayed at three parks in three years for a total of four nights - and received a better discount with Escapees than Good Sam or AARP (Twice I've gotten a better discount for AARP than Good Sam or Escapees).
I'm retired US Military - so I can and occasionally do - stay at campgrounds on US military bases. Sometimes these can be very much cheaper than other campgrounds - $20 per night at Newport, Rhode Island (30/W - no sewer, no facilities except a place to park the trailer).
When looking for discounts - our primary source/ option is Passport America - again - life members. In 2016 we've stayed 9 nights at PPA parks for $181.15 - avg $20.13 per night. For 2015 it was 8 nights for $169.96 - avg $21.25. For 2014 it was 2 nights for $43.91.
We also have a full membership in Thousand Trails. Which we have used for 57 nights this year, and have 37 nights reserved for the last two months of 2016. Using TT that much will lower our average per night paid camping cost from $20 per night to $15 per night.
Finding 'cheap' or 'better priced' camping take some work. There is no 'one answer'. You have to look at what options are available along your route, and make your choices.
As an example - when we departed Capitol Reef NP for Arches NP a few days ago, I had two options for fuel - paying $2.699 per gallon along the shorter route, or $2.529 per gallon along another route.
The fuel savings for the cheaper fuel would have been about $5.10. The route was 40 miles longer for the cheaper fuel. That would have cost me 4 to 5 gallons extra fuel usage. So the 'cheaper' fuel would have actually cost me about $5 more.
Those are the kind of numbers you have to be able to look at if you want to 'save' money while traveling.
Full-Time 2014 - ????
โNot all who wander are lost.โ
"You were supposed to turn back at the last street."
2012 Ram 2500 Mega Cab
2014 Flagstaff 832IKBS TT