We don't like dressing up. Are not posh. Like to chat a bit but not keen to spend every evening talking to others. Neither of us really wanted to go on a cruise but we did want to see the Norwegian fjords so we decided to go once. We went with Saga and loved every minute of it. Have been twice more since and have another cruise booked.
Cruising is not for everyone it depends what you are looking for in a holiday. Many people love to relax and sun themselves on some exotic beach. Others like adventure holidays and exploring. We enjoy relaxing, reading, eating good food, drinking nice wine, looking at beautiful scenery (even if it's raining most days which it did on our first cruise), listening to some interesting talks and chatting with people in a relaxed atmosphere.
If you do like cruising, I imagine a lot would depend on which cruise line you travel with as to formal nights, tips dining etc. We happen to have been lucky in trying Saga first and it just suits us exactly.
ethelbags, whatever you decide to do for a holiday, I hope you enjoy yourself.