You can check out Marriott's website at Membership Benefits to see what the stated benefits are for each level. You'll note that the Silver doesn't have a lot of "real" benefits. Since Marriott almost gives Silver level away, that seems reasonable. For you, if you aren't staying at Marriott's very much, then the few benefits Silver does have (reservation line, reservation guarantee, bonus points, late check-out, etc.) just won't be of big help to you.

With that said, the card does have a few benefits for you. One you will get around 20K bonus points, a free night coupon, etc for getting the card. There are three different versions of Marriott branded Visa cards. A search can get you the pros/cons of each card. Another benefit that the card can get you even if you don't have a lot of hotel stays during the year is I think that if you pay your annual Maintenance fee, if you use the Marriott card, it is treated as a Marriott purchase, so you will get extra points that way. Plus I do believe some purchase their MVCI ownership using the Marriott card, as much as possible, to get a whole lot of extra points as well.