Ken,

I'm going to re-do our shower, using tile. It has an acrylic shower
base which I want to replace.
Should I go with acrylic again, or do tile? What are issues regarding
durability, lifetime, leaks, ease of keeping clean?

A prefab acrylic base will certainly be easier to install. No debate there.
But, you will be limited to a choice of sizes and shapes, and they can be
fairly easy to scratch. They also don't "feel" very solid.

Since you are tiling the walls anyway, I would choose to tile the floor
too. I built a large (6'x6') curbless shower area with a sloped mortar bed
and 2x2 mosaic tiles. It looks great, is very durable, and I would not have
been able to find a prefab base for that. I used a waterproofing system
called "Kerdi" which is fairly easy to install and works very well. It goes
right under the tile and keeps the moisture out of the sloped mortar bed,
so you don't have problems with mold and mildew.

Grout can stain and discolor over time, but regular cleaning and periodic
applications of grout sealer can help with that.

With either option, it's usually the caulking that mildews and discolors.

Check out the John Bridge Tile Forum at
http://www.johnbridge.com/vbulletin/...d=1&daysprune=

There's a lot of great folks there who can offer lots of great advice.
Somewhere deep down in the forum you can find the thread "Anthony's House"
which details my tiling experiences on our home.

Take care,

Anthony