Redweek is good because it's a very popular listing service. You will get lots of eyes on your ad, and will probably see a dozen competing ads for your same resort and week. Go and check it out.
What you won't see - how much a week actually rented for, so you can't rely on the ads you see as an indication of what you will get for your week. You should be listing on TUG no matter what.
The basic rental listing is pretty cheap. Redweek just connects you to the renter. You have to provide the rental agreement, get the rent payment, put renter on reservation, handle a renter that backs out, etc.
The Full Service is more expensive but Redweek works with renter on your behalf. You still sign the rental agreement (Redweek generates it). Renter can pay with credit card and money is held until the rental completes, so there is an escrow involved. As an owner you may not like that, but you don't need to worry about payments being disputed.
There will be some work from your end even if you use full service. You will need to show Redweek confirmation of the week (i.e. reservation). You will need to approve or deny offers in a timely manner. You will need to contact Marriott to put renter on reservation and show proof to Redweek. These are all things you would normally do when renting your unit.
Redweek doesn't actively go out and try to find renters; it's just a listing service. Since you are competing with other people renting the exact same week, set the price accordingly. If you have the lowest price you WILL get offers, especially for a high demand week. Ask a high price and yours will be the last one getting a response. As the week approaches, all owners tend to lower their asking price, so check the site often. I've never failed to rent for more than MF ever using Redweek.