Hi, we booked on the OV2 last Aug. and it was fab. our grandaughter (15) came with us but said she did not want to 'dress up' every night. there are no formal nights but everyone was smart casual. Our shared cabin for 3 had loads of space (much bigger than the balcony one on the oceana this year)and a very spacious bathroom. the food was fabulous, entertainment could have been better. the only thing it did not have was a cinema which i believe is on OV. all in all our holiday was great no complaints. grandaughter looked on as we docked and asked why we wern't on one of the 'big ships'. she now says when we take her again she would be quite happy to 'dress up'.
OV1 has a dedicated cinema, OV2 has a bigger Spa. OV1 has dark wood in the cabins which looks kind of dull whereas OV2 is light wood and therefore feels brighter. Cabins are particularly large on OV1 but OV2's are also bigger than many new ships. It is therefore down to where you are going. I am guessing that you are going to the Caribbean. You will be busy sightseeing or lazing on a beach all day so the dedicated cinema will only be used if you prefer films to live performance in the evening. There is a spa on both ships but OV2 is very very good. Prices are not cheap so would you be using it during the day or evening to make the most of it? You only have 1 sea day and you will be busy getting to know the ship, unpacking and getting over jet lag. Go on the ship with the dates that suit you and the itinerary that gets your imagination the most. From experience I believe that this winter the best itinerary is on OV1.