I use the clear plastic shoe boxes and put one directly under the pipe and hoses if I can. I filled the rest of the area with plastic containers to put bottles, cleaners, etc.. When I have to clean or have a plumber in it so easy to slide out the containers.

You should not need something on the floor of the vanities to protect from water and condensation. If there is water and condensation, nothing is going to save the cabinet. You are protecting the area from the ick on the bottom of cans and other containers.

If I had brand new cabinets, I would buy the liners sold in Home Depot and other big box stores specially designed for these areas. I am linking to a discussion on the Kitchens forum about liner trays.

Here is a link that might be useful: Liner trays

Peel-and-stick floor tiles?

You need something to catch the drips if something springs a leak. It is a personal choice, I had 3 water problems at my last house and don't want anymore. I feel more comfortable knowing a leak will be caught. I check often to see if there is a leak.

The previous owner of my home got scrap pieces of sheet flooring (some old linoleum, some vinyl) and cut it to size and also used it in the drawers of the bathroom vanity. The material is just placed in, not glued.

The Rev-A-Shelf trays seem nice but are expensive for pieces of plastic.

Here is a link that might be useful: Rev-A-Shelf

I use the Rubbermaid plastic dishpans to hold all the normal "under sink supplies". I have two under both the mudroom and kitchen sinks, and one under the bathroom sink.

All the cleaning supplies sit inside the dishpans. If I need to clean out from under any sink in a hurry, I just lift the pans out.

When I first started using these pans I lived in base housing that had just gotten brand new cabinets. They were so beautiful and pristine inside; I was not going to mar them. When we moved, seven years later, the housing inspector would not believe me when I told him how long we'd been there. "But the cabinet floors are spotless!" Of course they were, nothing had ever touched them except the undersides of the new and always clean dish pans.

Caroline, you are like me in that regard. When I sell an appliance of any kind they are like new. A realtor was in my 9 year old home, she said it's fresh, still like new. I really appreciate what I have and I try to keep it looking that way.

Thank you all for your responses! Lots of good ideas here. My goal is to keep the cabinet base looking like new!

Like others, I use various plastic boxes under the kitchen sink and bathroom sinks and make sure one is right under the pipe in case of a leak. And it's just a matter of sliding the boxes out when you need a plumber. ALSO, buy some water alarms. I have them under all the sinks, behind the toilets and in the laundry room. Everyone needs water alarms!

To protect the wood floor base from water in bathroom or kitchen cabinet sink, you have to cover the bottom of cabinet with peel-and- stick vinyl floor tiles.

If you have a leak, that kind of stuff will not stop the damage. Water will find a way to go down and under the flooring under the sink then onto somewhere else. I has to be caught in something.

I get a solid piece of scrap linoleum from Lowe's, cut it to fit, then put thumbtacks [with a hammer] in. Easy to get up if needed, and keeps things very neat. Nothing is going to protect from leaks, but this is easy and cheap to install and stays in place well. Have used it in 2 homes and works great for me. Then I used the plastic crates to separate my cleaning supplies to keep them organized.
Judith