We just moved our washer/dryer to our upstairs bathroom by taking out a closet which made the bathroom larger. One thing you might want to consider is a floor drain in case it ever overflows. It's a great fear of mine.

We looked at a plastic washer pan and a number of other options but the floor drain is best for us. We had the flooring gradually sloped in that corner of the bathroom with plywood and mudding - then lino over top. The washer sits over the drain so you don't see it. It is such a gradual slope a person doesn't notice it, but is a 2" drain that should work well if ever needed.

We then caulked along the walls, then baseboard, more caulk.

I would consider putting in the plumbing for this drain while you have the kitchen ceiling out.
Last night is the first night with the bathroom finished and I LOVE the washer/dryer being across from the bedroom. It was the best move ever - especially considering how much larger it made my kitchen.
Good luck!
Maria

Thank you. It does make so much sense having the laundry on the same floor as the clothes!
If I install a 2" drain for the washer, can I use the separate shower drain (that currently connects up to the tub drain) for the drain pan under the washer that goes to a drain. Can I just sit the washer in the old shower?

I will check with DH tonight on the plumbing stuff - not sure about connections, etc.