SA blends brilliantly with most of what I have. I'm a big fan of string layering so I'll normally combine stuff from the metropolis series, mural, CSS, fluid shorts, depending on the cue. The sound of Air works really well with other stages like the Tuldex from OT, so layering w/ SA shouldn't be an issue. I think if you go towards the Orchestral Tools collection or the SF collection (Berlin / SA Symphonic Collection), you'll be in really good hands. The other one (CSS, etc) is also great. I use those all the time. Both routes you listed are great, you can make great music with either! Also, from what I've heard, HGW tends to lean towards SA, but I believe he uses private samples as well.