I had no idea Cultured Marble was a DIY! Out here it's only sold custom/installed.

We adore Swanstone, but installing Cultured Granite (sold by CM dealers) in a custom counter/sink/slab surround/neo-angle showerpan was cheaper than just the materials cost alone for Swanstone.

Swanstone is more durable than CM, hands-down. We have a tan granite-look to minimize scratches.

I have a new Swanstone bath/shower surround. I suggest that when you order it you are going to order the right size. Your experienced friend can help you measure so you get it right. I ordered ours from Lowes with a Lowes 10% coupon on their website ('moving discount'). There will be no need to cut Swanstone since you will order the kit the right size.
Their website shows all the options, then the Lowes plumbing person was very helpful when I placed the order. First I showed my contractor what I wanted to order and he verified my measurements.

Swan Corporation website
http://www.theswancorp.com/

Lowes moving discount coupon
http://www.lowes.com/cd_Offers+and+Services_425333486_

We had custom cultured marble in our last house and we have finally decided that is what we are going to have our showers made of in the house we are currently building. It was wonderful to clean and always looked nice. Our shower never had scratches in 13 years of daily use. Our matching garden tub also looked new as well. However, if you are not careful, a cultured marble vanity top will show light scratches, sort of like a patina. I never used anything abrasive or harsh to clean them with.

I am a huge believer in do it yourself. In fact, we are doing most of the construction on our house ourselves. However, in the case of either a cultured marble or Swanstone shower, I highly suggest a really good professional to do the installation. I understand the marble panels are quite heavy, and the stuff isn't cheap.

I have no experience with Swanstone, but a kitchen and bath designer I have gotten to know said her husband had insisted on Swanstone for their showers, and she said she finds the matte finish is very difficult to clean.

I know you haven't asked about tile showers, but thought I would add that I have always loved the look of a beautiful tiled shower....when new. I am someone who loves and prefers natural materials. However, I hate the upkeep and sooner or later the grout is an issue.

We considered Corian for the showers but ultimately decided to have custom cultured marble showers in the house we are currently building, since I know that it is so easy to maintain, and it also looks nice. It also lends itself to style blending (as I'm sure Swanstone does). I like the "unfitted" cottage look, so I am considering having a large console fireclay sink rather than a standard matching vanity since the vanity gets a lot more wear and tear than a shower does.

My suggestion would be to see if you can take home some actual samples of materials to test out. You will also find that it will help you make a final decision. Sometimes you just have to follow your heart.

I've had a Swanstone shower in my MB for 18 years. DH installed it himself. LOVE IT!

I don't think its hard to clean at all, and the matte granite look we ordered doesn't look like plastic - but it does feel like plastic if you tap on it. It was fairly expensive then, and still is, but we ordered it because it was to replace a tiled shower that leaked (did not want to go that route again) and corian was way out of our price range.

To me cultured marble brings back memories of cheap, throw it together bathrooms. Granted, it was forty years ago and what is old is new again but I could never use it because of that.

I think you'll be happy with whatever choice you make.