First off, is there any law (in Massachusetts) that a 2 bedroom unit has to have a TUB (as opposed to a step in shower)
Secondly, regardless of law… what are your recommendations?
On one hand, I figure I might be losing out on potential tenants (with young children) if I don’t have a tub.
On the other hand, that might not be a bad thing. 
TIProps,
A couple of weeks ago I bought a property that didn’t have a shower. It had a very small bathtub. You can buy a kit that will allow you to have a small tub and have a shower.
Having a shower is critical. It is FAR more critical to have a shower then a tub. You will have a hell of a time trying to rent a property without a shower. I would never take a bath everyday, and I would guess neither would you or your renters. If you want to choose one or the other then 100% you need to choose the shower.
I would do what I did with the small bathroom I was dealing with. Go to Menards and Lowes and try and put a small tub with a shower in it. The shower bars are shaped in a rectangle and connect to the celling and walls allowing you to have a shower curtain. But you have to at least have a shower.
I think the tenants will want the option to do both, leaving one or the other option out would limit your tenant pool. As you said people with kids need a place to bathe their kids. Also some like to take a bath to relax from time to time. And a tub without a showerhead is useless, I know I don’t have time to take a bath every morning and I would think most other people are the same way.
In my situation there was a small bathroom with no shower, just a tub. The last owner rented the place for $400 a month. I bought it and put a shower in the next week. Having the bath tub and shower allowed me to raise the rent to $500 + util. It rented out right away. But had I left it as a tub only, I would probably of had to kept the rent at $400 + Util. Even if I would have turned it into a shower only I would have had a harder time renting it.
If you have a very small bathroom and don’t think you can get a tub in bathroom then I would check store (several if need be), they will have some smaller tubs you can buy and then install a shower ring connected to the wall and/or celling which works pretty nice. But I don’t see any benefit to having just a shower or just a tub Vs. a little extra work and having both.
Maybe I wasn’t clear… by FULL TUB, I meant something you can soak in as well as take a shower.
I never meant to imply just a tub (without a showerhead), as that would be stupid. ;D
I decided to use the full tub option. I figure this gives me the most appeal to potential renters.
TIProps,
I overlooked the “FULL TUB” in title of your post. Either way your question was answered.
The property I bought went 75 years with no shower, just little a tub. Renter after renter with no shower. I agree this is stupid, but there are a lot of stupid landlords.