There's the click on the blue box and make it green technique but that's pretty limited...
also, can the bridge or whatever is picked get a different mix on the last chorus.
The blue/green marker is only one way to add/change instruments for your bridge. Each track in the BIAB mixer can have as many as 10 different instrument changes. You can create your own medley of various instruments that will play for a specified number of bars and change to another instrument, play on specified colored part markers to change or create your own custom medley.
You can have an instrument appear to move about in your song by having the same instrument appear in different areas of the song on different tracks that are panned differently.
Another interesting technique is to search for a particular artist so you have a list of the RealTracks sessions the artist appears in. Often you will find the artist plays the same instrument with the same setup across several different RealTracks. This fact allows you to spice up that instrument in your song by changing between the various RealTracks throughout the song. This effectively provides different strumming patterns in a rhythm instrument, different solo's, different picking patterns and will add life and more realism to your recording. It's a particularly wonderful technique to use for Bass parts.
A great example to see how the technique can work for a bass is Stealers Wheel song, "Everything Will Turn Out Fine" available to hear on YouTube.
Everything Will Turn Out Fine - Stealers Wheel Don't overlook taking note of other artists that may consistently appear in RealStyles along with the artist you're searching. Many times you'll find the two artists are playing complimentary parts against each other and will produce really nice tracks together.
Finally, when searching by artist or similar style, you find a particular riff or phrase that you like and will work in your song and fits seamlessly because it is by the same artist using the same instrument, you can capture that riff or phrase and make a loop to use within your song. BB RT's provides hours and hours of pristine audio in isolated tracks that is prime to take audio for loops from.