What is a good size for a new tank?

40 gallon and up is fine....

Theres no need for the wet/dry filter however. Most marine aquarists choose to go with LR and one or more other "filters" like a deep sand bed, or a refugium.

A 155g bowfront could make for an awesome marine tank if it was properly set up - lots of nice live rock, etc.

If height is a problem, you may be able to modify the stand or build a new stand that would lower the tank a bit. Or, do what I do...use a step stool. I can't reach the bottom of my 100g (56" high overall and I'm about 5'11") when I'm standing on the floor so a small step stool comes in very handy.

About those water changes - if you go with a large tank, you may want to consider stuffing a 20-30g trash can in a closet and using it for mixing and storing your salt water. And, if the trash can is close enough to the display tank, you can use a powerhead and a hose to pump the new salt water into the tank/sump. You could also use the powerhead and hose to pump the old water from the tank/sump over to a sink drain or something. Viola - no more buckets!

Oh well, just throwing some ideas at you

I agree with Greg--that would be an awesome tank!

We have a 180 setup, and use an agriculture sprayer tank for mixing water for changes. It's on a cart, so we just store it in one room, and pull it out for changes. It's raised enough that you just open a vavle on the bottom and gravity pulls the water into the sump. Really easy!

And--I am 6'1, and use step stools when working in the tanks. It's just easier, since you don't have to worry about accidentally leaning on the tank, or trying to tip toe it.