Cuba is a great destination but I am not sure what it would be like for a honeymoon though.
My first piece of advice is to avoid booking a package deal as you would almost certainly end up in Varadero which while is a really nice resort, you do not see the real Cuba. By all means spend a few days there if you want to have some relaxing beach time but do not go to Cuba for the beach alone, otherwise you would be far better going somewhere like the Bahamas or St Lucia.
We were in Cuba almost 3 years ago; flew with Air France whom I would highly recommend.
You need to have at least 3 nights accommodation booked before travel or otherwise Immigration will book it for you at an hefty mark up fee.
You need to obtain a tourist card (basically a visa) prior to travel; you can get this at the Cuban consulate off the Adelaide Road in Dublin.
Would definitely recommend hiring a car to travel around the island; best way to see the country.
Places to I would recommend you go to:
- Havana - Old city
- Trinidad
- Vinales
- Varadero (if you are looking for a beach stay)
Apparently Santiago de Cuba and Cienfueguos are also worth a visit but we were not there so I can't comment.
One last thing, Cuban food generally is quite poor even in the top resorts. From what I hear, it has not improved since we were there. You will find the odd good restaurant if you really look particularly pizza places.
If you have any more questions, send me a message and I will be happy to help