I think about this every summer. I am 51 and I only have bikinis -- I discovered them about 5 years ago and found they were best for my straight body. It's hard because every year my stomach area becomes less appealing to me, but it's so difficult to give up the bikini! One-pieces are so difficult to put on (for me) and feel good in. They are unkind to my small chest, and they seem to accentuate my midsection more than a bikini does (explain that one to me). Even though I live on the coast I don't live at the beach in the summer -- so it's just a few visits really, and I doubt that I will do anything this year but don the bikini once again. I do think that after 5 minutes you stop caring and start enjoying the beach anyway.
PS Much of my continuing enthusiasm comes from Runcarla's bikini photo from last year, which is TRULY AMAZING. She is an inspiration to 50+ bikini wearers -- so, so, so gorgeous.
PPS DD the younger (age 20) just moved (back) to Hawaii for the summer. She was especially excited to be going back to the nude beaches. "I can't wait to tan my boobs again!" Ah, to be that comfortable with one's body. Pretty amazing.