I'm a 61 year old too with a preference for nicer ships. The three upscale but mainstream cruiselines I'd suggest looking into would be Celebrity, Holland America and Princess. The smallest ships we're talking about are in the 50,000 to 61,000 ton range for Holland America, sorry I don't know the low end of Celebrity ships, but they have two at 77.000 tons, and one at 91,000 tons and Princess whose ships range in size from a tiny 20,000 to a mega 109,000 tons. If you can afford it, have your travel agent give Crystal a look. Very often you can get some nice bargains on the line and it is very upscale and according to reviews all over the internet, an absolutely delightful cruise experience.