We've done a few cruises and seasickness has never been a problem on them. (unlike cross channel ferries) Porthole or a window is nice but not essential. We had one brilliant family cruise all four of us (dcs were big teens at the time) in 2 bunks below decks - the tv screen showed us what was happening outside (sea!) There is so much to do all day, and such nice public rooms that you will probably only use the cabin to sleep in.
I think sea sickness depends where you go cruising. I've been twice in the Caribbean and barely felt the ship move because the water is so still and the weather so good. There isn't any 'bobbing around,' it takes a hell of a force to rock a cruise ship! I went on another cruise around Cape Horn and as you would expect the weather and sea were really rough and loads of people got sea sick. If you're going on a hot weather cruise I think your DH should be fine on the sickness front.
I don't think top, middle or bottom makes any difference, although generally speaking the higher up the ship the higher the price. There is something to do on every floor so even if you are low down you aren't too far away from the action. Your main decision is whether you feel you will benefit from shelling out the extra for a balcony. Personally I do because I really enjoy having a morning coffee out there and sleeping with the balcony door open listening to the sea, but there are plenty of others who don't see the point in paying the extra because there's so much to do elsewhere on the ship, you don't really end up spending much time in your room so it doesn't really matter if you haven't even got a window.
Good luck with your cruise shopping, I'm very jealous!
Ships aren't like other boats - it has to be pretty rough for a large ship to move a lot. If you want calm seas avoid transatlantic, bay of biscay etc. Go for the Caribbean or med. To minimise how much movement you feel you're better to be midship on a lowish deck. I would pay extra for a window but would only bother with a balcony if there was something worth sitting looking at - fjords for example. Imo not worth the extra to look at endless sea. Where are you thinking of going?
Not been on a cruise ship before, but really do like the idea. I've got 2 burning questions that I hope some of you may be able to help me with. The first is about being sea sick, dh say's he does not do boats due to feeling sick and feels that a cruise ships will make him feel the same. Is this true? The second is where on a cruise ship would you opt to stay, by this I mean would you book a room at the top of the ship, middle or bottom? I suppose I'm asking which is the best part to stay in and is it worth paying all the extras for balconies etc?