Doc;
We have the same issue, as my first mate retired a few yrs ago, and I joined her in retirement this year. We struggled with what to do in our retirement for a nanosecond or so, and here is what we have come up with.
Keep the boat. No matter what else we want to do, it will never trump cruising the BC coast in the summers. She wanted to buy a winter home in the sun and snowbird. I, OTOH, am leery about Real Estate in the US right now, and I haven't seen much of the states, so an RV was attractive. We looked at various sizes and shapes of motorhomes for the last few years, and every cheap one we toured pretty much soured our expectations. Last March, we vacationed in a house in Indio Calif, and since I don't golf, I looked at all the motorhomes I could in the first 2 weeks. My take on them is that you only get what you pay for, like boats, so unless you are happy with a terrible ride and crappy looking inside finishes, start looking in the highest price you can afford. The better ones (I equate better with bigger after looking at so many) all have diesels, and once they have a diesel, they don't get blown about by big trucks, so the tag axle is a non issue. The big ones need a tag axle to carry the big weight anyway. We found the RV market quite depressed, so were able to get what was at the time a steal of a deal on a 13 yr old Diesel, high end Motorhome. Of course, having spent our money, the prices are even lower 6 months later.
The toughest part to predict is the quality of the places you will end up in. So far, for us, the places are generally a disappointment. You really need to book ahead, and to get a better rate, a longer booking, like a week or a month will significantly cut the rate. Anchoring out is rarely an option, unless you are just travelling and spending long days on the road. A crappy marina is far better than a crappy RV site, as at least you have a great view.
We have just returned home after spending a month in California, in a higher end place, and all was good, except the total lack of social contact. That surprised me, as when we go boating, there are always friendly people at whatever place we end up in, but in the RV site we were in, most of the people there were owners, who kept to themselves or their pre-established social routines, to which we were never invited.
RVing is quite a bit cheaper than boating, in capital cost and in annual cost, except for depreciation, which is huge, no matter the age of the unit. I figure my boat has retained most of its initial cost in present value, all I have lost there is the inflation on the money, but the RV, because there are so many of them, has a steep depreciation, exascerbated in a tough economy.
A few years of this split personality before we have to pick one. I expect when the time to choose comes, the boat will win.