Good to hear you chose wisely! :)
If that's the sort of camping you'd like to do, perhaps take a look at Thousand Trails. They have a CG next to the ocean just down the street from the KM CG in Ocean Shores. Some of their CGs are pretty nice, some have lots of activities for kids, many/most have large sites. Their CG in Birch Bay is one of the tidiest, well kept and best managed of any CG we've been to anywhere so far and has super friendly staff. Some can have outdated electrical, water or sewer but has never bothered us much. T/T has more CGs that you can travel around to in WA & OR than KM, plus across the US and one in BC. We've been to quite a few T/T now from BC down to Gilroy and over to Vegas.
Don't buy a new membership, look for a pre-owned one. We got ours on Craigslist for $800 but prices can vary. Older memberships can have better features and benefits too such as frozen dues for life and being able to move from park to park and stay in the system continually. Contract details vary a lot and you need to get the memb. no. from the seller and contact head office to verify all contract details. You can buy one from anyone in the US. We got ours from someone in AZ. No problem selling a memb. providing you follow the particular contract's terms & conditions (for ex. like selling to a family member only). There's one or two websites that explain in detail what to look for in pre-owned T/T memberships. It's a very inexpensive way to RV and to visit lots of different places. You could go spend a weekend at a few of them at retail pricing to see what they're like. Now is a good time to buy one before the season starts up. We wouldn't get rid ours for anything...