Hi Elizabeth,
Welcome to the world of Omega !
I'd say a Speedmaster is a great choice. But that really is my personal opinion. I have no idea about your or your husbands tastes, so can't really comment on what suits you/your husband.
I'll concentrate on the Speedmasters here, maybe someone else can do the Seamasters.
I can offer some impartial advice & some info about the various speedmasters out there.
Firstly, I'd say, unless you are experienced & know what you are looking at, or you have a watchmaker that you trust implicitly, I'd advise against going for a 2nd-hand (or vintage) piece. If you can afford it go for a new watch. Your husband will NEVER forget this gift.
There are various Speedmaster models out there.
Here's a link to the Official Omega Speedmaster webpage
As you can see Omega list 11 "types" of Speedmaster & within each of these "types" there are also metal/colour/strap/bracelet variations.
Lets go through the "types", with a few notes to each.
So, that's basically the choice of models.
If I were you I'd take a look at the models in an AD in NYC. I realize that this maybe a problem if you want to buy the watch as a present, but I'd really recommend it. Guessing at what you husband may want/like could be a costly mistake.
You can find the NYC dealers here.
You really have to take your time & try the watches on in person to get a feeling for them. I'd ask for a Catalogue & price list, then start trying on the various watches. ( take a pen & write in the catalogue - or cross models off - as you try them on )
I'd then go home, have a think about it & then call "our favourite AD".
I'll ask "turbinator" to send you the details ( or look for a post from "Turbinator" on ths forum). We have an "out of state" AD who will give you a great price on a new Omega. This guy is 100% trustworthy & an official Omega AD. You will have a real job to beat his prices. MANY, MANY people here have bought watches from this guy & I have never read a bad word about him.
Whatever type of current Omega you choose, "our favourite AD" can provide it.
Finally Chuck Maddox lists most of the "newer" limited editions & releases in the speedmaster area on this web page
Let us know what you decide & how you get on.
Your husband is a lucky man. I got taken out for a steak for graduating :-)