May I suggest Sonic Fire pro; it's not a conventional library of fixed needle-drop music. Instead, it is loop-based with a self-assembling algorithm. Pick any duration you need covered, you're not limited to hard 15 or 20 or 30 second bites. Need to cover 7 minutes and 2 seconds? Bam, done, and not just done; it offers you between one and six or so alternate versions, plus, you can further customize the tune in a menu that takes out the drums, strings, vocals, whatever. Want a version pitched to leave a frequency "hole" where the human announcer voice will go, and be easy to hear? One click. Edit changes mean the track needs to be shorter? Type the new duration and bam, done again.
Now, you used to have to buy disks of source clip collections to "feed" this program it's custom loop clips, but now you can skip that and have the program select from stuff you have locally, plus a large and growing library on the web: pay for the songs on a buffet-style pay scale. No copyright issues; everything is cleared. Some of it can be sound-alikes to better-known tunes you can't afford the rights to.
Requires no music knowledge: it walks you thru menus of adjectives describing what you're looking for, whittles it down and presents the best fitting options, saving hours of auditioning. Though, if you have even a modicum of musical ability, you can plug-and play-with their loops like musical legos, and build even more customized tracks, say, with a cymbal crash or horn sting to go right where you need it.
For corporate/government/institutional use, I think this is a hugely economical and flexible system, way better than buying libraries of songs where the bulk of the tracks are never even put to use. I don't care if this sounds like a commercial: Sonic Fire is like having a composer and band on hot standby in the booth, waiting for you to tell them what you specifically need.