Thanks, Pak - that's an interesting way of looking at it. I think since Cap is 'bigger' (and has less installments to continue fleshing things out), I'd probably go with the film being the one I'd rather have 'unspoiled' (particularly since I can watch 'Agents' ep 17-on immediately after).
k1, I have gotten so good at avoiding spoilers I actually have not seen a trailer for CapAm:tWS.

I avoid even trailers for any film I already know I'm going to be watching. And I have a DVR with DVD-burning capability, so they are already backed up, just waiting, so no pressure to watch (from that, at least).
My spoiler-avoidance developed into 'tactical viewing' of newsfeeds and other means of sharing info about upcoming [TV/film] after the end of Buffy season 5 was revealed in the subject line of a post on the Buffy newsgroup - over three months in advance of that final season 5 show airing. [
My ideas on avoiding spoilers for a theatrical presentation in case anyone is interested in the degree of tactical thinking I take this to.

Interestingly, I didn't mention 'avoid trailers for it' in that post... probably not relevant by that point.]