There are some great Z fares out now for BF that preclude you having to use miles ,give 150% EQM and you dont have to wait on clearing an upgrade list.I always prefer these to rewards.
The benefits to Silver I can ascertain for you is the mileage bonus you recieve from that status, an occasional domestic upgrade(after Plats and Golds so probably rare ,esecially on well travelled routes)and maybe better award availability on the rewards charts. I know plats have a better selection. Staus also allows you to have a preferred seating chart in coach.For $350.00 I would probably just tell them I had long legs and get an exit row that way.Finaly ,there is an elite reservation line that is not always better ,but the wait seems shorter