BradMM,
Why not just rent out the lake house? If you didn't use the lake place will you actually use the Caribbean home that is further away?
It's hard to know how to answer your question without a complete financial picture. If it were me I would sell the lake house, Invest in good index funds or whatever would be appropriate with your current retirement situation. If you sold the lake house for 200,000, invested in index funds that could return a moderate 5% then withdrew 4% per year you would have:
A.) Your original 200,000
B.) 8,000 per year to vacation with.
C.) An extra 2,000 per year from the extra 1% difference between the 6% return and the 4% that you take out. By the way, you would also tack this 4,000 on to the 200,000 so the second year you would have 202,000 which means the 4% you withdraw in the second year would be worth 8,080 and so on for ever as long as the market is fine. If the marked dips take less than 4% so that your principal always stays above 200,000 and is growing.
Different strokes but I wouldn't touch rental property at age 60 with a 10 foot pole. I'm 54 and at an age where I could walk away from work without looking back and live the Mustache life. My only goal at this point is to not screw up what I have accomplished so far.
Best of luck with whatever decision you make.