Let me preface this by saying that I'm not a lawyer, I don't even play one on stage (though I played the bailiff in Inherit the Wind in University), so any final contract you craft should be vetted through a lawyer to ensure that the rights you want to retain are retained. So, with that, here are some thoughts that I'd have in this area:

If the client hasn't asked for exclusive use, I wouldn't just give that to them. I'm not a pro, but my spouse is in the advertising industry and exclusives are usually more expensive because, in effect, you're assigning copyright to them, or may as well be. That's not necessarily a bad thing, but don't do that as a toss in!

In any case, variations to consider are:

1. Exclusive in perpetuity.
2. Exclusive for a set time period.
3. Unlimited, but non-exclusive, in perpetuity.
4. Unlimited, but non-exclusive, for a set time period.
5. Any of the above, but limited media scope.

From a general professional services concept, we're looking at (at least) eight options in a contract for the outcome of the creative work. I would work out those contract formats with a lawyer and then negotiate with the client for the type of contract that they want. Once you agree, present them with the appropriate one to sign. Now, of course, you may also encounter a situation where they offer you a contract and you have decide if the terms are acceptable. To be honest, I think that's a lot easier to deal with, it's going in with eyes wide open, but odds are they end up owning the end result.

One final consideration, do your level best to ensure that you can use the work in your portfolio unless, of course, it's not a shoot you want to brag about...