Thank you for the replies. Sorry that I didn't explain very well, I wasn't quite sure myself what I needed to ask. I had the plumber install the cpvc lines (hot and cold) going (in/out) to a new water heater (we moved it over about 6 feet from its original location). It is in the garage.
At the time, I had not decided on how I was going to setup the washer/dryer and sink layout so I ask him to install the 1/2" T to these main 3/4" lines so that I could later install them myself, without interrupting the flow to the water heater. I had him install 1/2" because that was the size of the copper lines. These two cutoffs would then be used as the cutoffs for the w/d.
While planning the layout I wondered if I would have been better off by having him install 3/4" T's instead. That way instead of going from 3/4" to 1/2" for the supply lines and then up to 3/4" again for the faucets, I could just go with the 3/4" directly to the supply lines. We don't use a lot of hot water for laundry and the wait for hot water in the sink wouldn't be a problem. ghesh, I hope I explained this better. Anyway, I thought that perhaps the larger lines would take more volume away from the house supply lines while in use (like the shower):D I am eliminating the extra faucet hookup for the w/d and tying the hoses directly to the shutoff T's, using a 1/2"-3/4" reducer and hose adapter. The garage wall where the supply lines run out is also the wall for the den. It only has paneling and I don't like the idea of having such a flemsy wall on the backside of the plumbing. I wanted to reinforce the wall (the garage door wall took a pounding from Katrina). I ran the piping outside of the wall and will have a shelf running behind the washer/dryer and sink to cover the exposed lines/drain, with easier access to avoid tearing out the sheetrock on the garage side. The adapters for the supply lines to the w/d and sink will be attached to the wall of the shelf. (like the new plumbing fixtures that are concealed within the wall). Again, many thanks for your help.