Should They Stay or Shold They Go? Selling with Tenants???

Does anyone have advice on selling a multi-family while I have tenants? I have a two-family I want to sell - I'm renegotiating the lease for one floor and they're staying month-to-month (their choice) but the other lease is up over the summer. I don't know right now if they plan on staying.

I haven't told either tenant I'm considering doing this because I don't want them to leave but I also don't want them to be mad if I resign the lease and then a week later announce I'm selling.

Should they both be on month-to-month leases? Or is it preferable to have at least one unit empty? Or does it not really matter if they are on year leases - from the perspective of someone buying. I think in my case, my market is more of an owner occupied situation.

I am a realtor but have yet to list a multi-family so I can really use some advice from other landlords.

And if anyone wants to buy a great 2 family that's been totally remodeled on the inside in West Hartford CT - have I got a house for you!