If you're not a DD fan, I wouldn't do it. There is uncertainty in the long term value of comics, so I'd only want to own books that I want to own regardless. I mentioned DD1 because I think it's still affordable for a first appearance of a major character (and I like DD), but it may not be for long, especially if DD finds himself in a Marvel produced Avengers movie (or even a new Marvel produced DD movie).
I love GSXM1, but those three first appearances in it are never going to be as big a deal in the market as Wolverine's first, IMO. If Storm, Nightcrawler, and Colossus were going to get a price bump, they would have already from their many previous movie appearances. Are any of them likely to have a solo movie? I like the characters because I like the X-Men, so GSXM1 is a must-own for me regardless, but I'm not holding out for any price bump due to movies or any other reasons. 30 years from now (your buy and hold timeframe), will those three characters have risen to some iconic status, maintain where they've been for the past 40 years, or taper off? I don't know.
As far as buying a mid-grade 181 is concerned, I think they will continue to grow in price as the higher grades become too expensive for many buyers. I think we're seeing that low-mid grade value bump going on right now. At least it's frequently brought up in the Bronze forum here. I do think 30 years from now that Wolverine is much more likely to have or maintain his iconic status, therefore I think he's the better bet from a long-term buy and hold value increase potential.