I've never used the express services to ship luggage to/from my destination, but I've used FedEx and UPS to send extra clothes (or send dirty clothes home) many times. Pack the clothes in plastic "space-saver" travel bags, take them to UPS or FedEx, buy a cardboard box onsite, pack it and ship it. Contact your hotel afterwards to make sure it will receive the box, and for what price (some hotels charge to receive and ship such things). If you ship to your destination, save the box and use it to ship the extra clothes back in the space-saver bags.

The added cost of the weight of luggage makes shipping in a box much more affordable. As for toiletries, I've never shipped them...if they are not Ziplock-worthy, I put them in a checked bag.