The Bain Ultra tubs (and I would think most airbubble tubs) are very low maintenance unlike many whirlpool tubs that need monthly cleansing cycles. Resale-wise I think alot of people are looking for a master bath with a tub that does something therapeutic, so I don't think it matters if it's air or whirlpool. If you're not worried about resale, I would say do what you feel is right for your lifestyle. Having the air gives you the choice of using the tub as a soaker or as a therapeutic option if your back is hurting, you've pulled a muscle, etc. With the soaker, soaking is the only option you have. I personally, like to leave my options open. Just my $0.02.

Another thing to consider regarding your layout considerations is going to an under-mounted tub. I was looking at 60 inch tubs to get a little more decking space and ended up going with a 72 inch tub that when it is under-mounted will give me about the same deck space as the 60 as there is 5 inches of flange all the way around the 72" tub (10 inches off of left to right and front to back, rectangular tub). I get the interior space of the big tub with the footprint of the smaller one. I will also say a little prayer to my favorite wrench to send a master plumber your way. All of us DIYers need all the help we can get.

"Pain" was not a good choice of words. Drop-in relies on solid, level carpentry (deck and frame), so as long as that's good and the drain is put in the right place, there should not be an issue. Somebody has to do the framing properly. Alcove tubs can be tough sometimes, such as when there's a foam base and the floor underneath isn't perfectly level. Then it can creak when you stand in it unless they foam it and shim it, install the stringer, etc, just right. Lots of trial and error sometimes. Dealing with this comes with the territory. Free-standing tubs are another thing altogether, since they just rest on the level, finished floor, then get hooked up. Just choose what you want, then find the right guy to do it. I think you are right about not seeing the apron of an alcove tub. I did a bathroom recently that did use an alcove tub with apron, and that was the biggest regret of the client. But we did not have the depth for a drop in, so it had to be that way. You, on the other hand, presumably have the luxury to do what you want. Go for it.

I live in a condo with concrete floors. I was also on the "architectural committee" which approved proposed renovations. Any time there was a proposal that would entail moving plumbing lines, we would insist on having a third party plumber/engineer review the plans at the homeowner's expense to provide us with opinions as to whether it should be done. We would also have required a covenant running with the land the warranted the change in plumbing in the event of any kinds of issues. Because of the extreme potential issues for plumbing changes most well run condos are extremely leery about doing anything that alters the infrastructure. For instance what happens when a homeowner on the top floor does some kind of Mickey Mouse plumbing and every unit below is flooded such the people have to move out while their units are completely reconstructed. I recently finished a remodel in my condo and I got rid of the tub/shower combo for a larger shower. This required a change in the drain - although it was located in the same position as tub drains are different than shower drains. As posted above, besides approval from the Board I also had to get permission from my downstairs neighbor to break into his ceiling so my pipes could be accessed. This cost approximately $1000 just for the demo and repair to my neighbor's ceiling. Luckily I am friendly with him and his ceiling wasn't special - just plain drywall. Other people in my building have "fancy" ceilings and approval to demo them would have been more expensive and potentially difficult to get.