I would suggest Princess cruises. The two or three formal nights are great fun, although if you don't want to join in the fun you could always eat in the Horizon Court Buffet. Room service is free and you have that option as well. There are many activities to keep your parents occupied. Great shows, dancing, art exhibitions, lectures, craft activities, golf links, tennis, many poolside activities, and the usual trivia quizzes and bingo. The rest of the time, is casual dining in the dining rooms and the service is very good.
I thoroughly recommend Princess, they go the extra mile to make things as comfortable and pleasant as possible for their travellers. I hope that your parents enjoy themselves, and may I also recommend taking a cruise that takes in the Panama Canal.
I would say RCI for a bit of American Glitz - so many bars, and good shows. Only 2 formal nights, and some very good speciality restaurants for that special romantic evening for 2. Look at Freedom or Voyager class ships for the biggest 'WOW' factor.
We love Celebrity one of the best in the market and most of their ships are in the top ten including our two favourites Century  and Millennium  with its external glass elevators, but what we like others may not but they are worth looking at, check out the Cruise Reviews and see what ohters say and if you can afford it look at the option of a suite, comes with a butler so a real treat. One of the most ideal areas to cruise is the Caribbean so long as their anniverary does not fall between July and October when it is the hurricane season which this year has lasted into November but it is lovely in this area even from January to May with temps 65/75 degrees and in some places slighty higher. Given it is a way to fly look at minimum of 12 day cruise and that way they will have 3 formal nights to enjoy.
Looks like you are from the Edinburgh area. Dancing, shows, a few formal nights, pleasant lectures and craft and art classes are really fun, good food and cruise staff that love the passengers. Try Fred Olsen Cruise Lines - smaller ships that would give your parents the opportunity to get to know other passengers - they are really friendly ships and some of them sail out of Leith oir Greenock which if your parents are in Scotland would save them having to travel or fly to join the cruise. I recently went on the Braemar and that ship is very roomy - a fair bit bigger then Black Prince and Black Watch.
Hi, Ive been on 7 cruises and could"nt fault anyone of them,the best one i would recommend for your parents is The Island Escape my husband took me on that one for my 50th birthday, 7 years ago and it was BRILLIANT! it had everything from relaxing by the pool to salsa dancing watching shows to things like Mr n MRS ,BINGO,CASINO MOVIES n late night eating in the 24hour restaurant,there just so much do and even he excursions are well worth the money! Well i hope this has answered a few of your questions and where ever they go i hope they ENJOY it.
We have been on 12 cruises with Princess Cruises. There are around three formal nights when its fun to dress up. The rest of the time its smart casual in the dining rooms but the Horizon Court at the top of the ship is buffet style and you can wear what you like there. There is always room service and dining on your balcony. Would thoroughly recommend them.
I suggest a Fred Olsen cruise, more so if they don't fancy flying.
can 'dress up' or not as you choose, entertainment and food is
very good, value for money, although shore trips can be expensive,
overall I think best company for older people.Med is best for
Well you won't go far wrong with NCL or PRINCESS Cruises. We have sailed with both and found not dressing up no problem and you don't feel out of place.
Hope this helps.
Been with Princess Cruises twice and loved it, dressing up 3 nights out of 2 week cruise is no problem. Did find that the Americans dont bother as much as us Britts wich we thought a shame.
Caribbean is OK if they don't mind 8-9 hours each way cattle class (or can afford to book their own flights!). Or sail each way on 21-23 night (or more) cruise with P&O from Southampton. How do they cope with heat - may be better going to Med later in season. Do they mind being surrounded by VERY large numbers of Americans? (Celebrity are indeed beautiful ships and provide a 5 star cruising experience but you would have relatively few Brits on board) Island Cruises and Thomson are at the other end of the scale - cheap and cheerful. One advantage of Fred Olson and P&O cruises is that onboard spend is ins sterling unlike most of the other more upmarket lines mentioned where it is in US dollars. Hope some of these thoughts help. (I have cruised about 16 times so could offer more info if required, but would suggest studying the websites of 2 or 3 companies and discussing the matter with a good TA.