On a river cruise, the pace is leisurely, the banks on either side are very close and you just glide by. Also very smooth. Great to be in the dining room, being served great food with great service, and having the scenery pass slowly. Try a Danube cruise from Budapest up to Germany.
Also, very small ships, maybe up to 160 total. Shore excursions are very convenient, buses right at dockside. Walk 100-feet at most to board buses. Also, no big mobs!
Cruises: 1-day to Greece Islands
7-days eastern Caribbean
14-nites Alaska to Los Angeles
7-days small ship Philly to Bermuda
10-nites Danube cruise
10-days small ship to Canadian Martimes
The first cruising I ever did was river cruising - nice tempo, very personal service and leisurely meals. No lining up for elevators - they don't have them! I have never had the need to use a bus when I left the vessel - just walked!