Alibo
I don't see why you shouldn't take your toddler on a cruise. We went P&O, with ds (aged 6) and the nursery facilities were great. They will take your child in the playroom for a while during the day if you want to sunbathe or do some of the activities aboard.
And at night time you can put him into the night nursery where he can sleep until 2:00 a.m. if you want. Just take him back to your cabin when you are ready.
Oh, and they did fab childrens tea at 5:00 each day.