The different parts of a corporate identity program can't designed in isolation. They are like the variables, object classes and functions you build into a piece of code, or the parts of an engine: they have to work together as a whole. For that reason, context is everything. A color can appear quite different in different surroundings, as many famous examples demonstrate. A typeface that is elegant in one context might seem merely weak in another. And so on.
It's a rare client who has the visual education and experience to be able to look at a typeface, let's say, and get a clear mental picture of it in use as signage. In fact, it's the rare designer who can do that reliably across all the possible uses in an identity program. Designers, just like programmers, test, test and test again.
For both reasons, an identity presentation is always done using mockups that are as close to the real thing as time, budget and practicalities allow, because the client must see everything in context. If a new identity will appear on vehicles, storefronts and catalogs, it will be shown on photographs of vehicles and storefronts, and on mockups of catalogs, so that the proposed combination of logo, colors, type, white space and proportions are easily grasped. Often, there's a great deal of money involved far beyond the design fees, so getting it right is important.
Your needs aren't so elaborate, but the principle is the same.
There are many websites offering pre-made mockup templates, such as Pixeden. They have high-quality Photoshop images of monitors, stationery sets, brochures, etc., that you can drop your own designs into; or you can create your own if you have the time and the Photoshop skills. The effort is more than worthwhile.
If you look at mockups of all your elements in context, you'll find it much easier to narrow your choice of typefaces. You can also do a bit of research: find some other corporate identities that you feel carry the kind of message you want your company to send to your customers, that have the kind of "look" you're after. They're probably using the typeface you should be using, or one very much like it. (There is nothing wrong with using a design trend to your advantage. If something adds an "instant recognition" factor to your corporate identity, it may be better to use it rather than something that's unfamiliar to your audience.)
When you have two or three complete mockups, any of which you feel comfortable with, then present them together, each one as a package. It may be that elements from one variation end up in another, based on feedback you get. That's all part of the process.
The most important thing to keep in mind is that no part of the identity program is independent of the others. You have to design them together and present them together if you're to have a workable, truly useful end product.