We've always had an oceanview room but have booked interior rooms for our kids. I found that you can get more of a sensation of the boat movement in an inside cabin. In order to avoid this (if you are at all sensitive to motion sickness), I would try and choose a cabin more in the center of the ship and on a mid-level deck.

If that's not possible, I would take the stern (back) over the bow (front) and I would take a higher deck rather than a lower one. Be aware that Royal Caribbean decks start with Deck 2 at the water level and go up; other cruise lines start with the lower numbers at the top, so make sure you are where you want to be on your particular ship.

Some long time cruisers I know will no longer 'waste' their $$$ on a balcony or deck (feeling that they are only in the rooms to sleep anyway) while others keep upgrading with each cruise.

On Royal Caribbean, the interior rooms are the same size as the oceanview rooms.

(ps- are you SURE you want to cruise with someone who 'doesn't want to see water'? )