Warming a SBD is probably done best using an Analog simulator/compressor/EQ, such the as the Waves SSL compressor, or the API Compressors or 550 series EQ's. Also a plug like PSP Vintage Warmer works great on certain material. Sonic Maximizer is another. The L3 on warm and cozy setting will work fine too, but it's much more transparent than any of the above. Don't be afraid to carve those peaks using the L3.
Putting a bit of light compression, such as 1.5 to 1 and then carving the peaks down to the RMS value or lower will give the mix a "glue" effect. It will also "warm" things up a bit. Follow that with the L3 to maximize and limit the peaks, and then add that to your Audience mix to taste.
Another trick is to use a Stereo Expander type of plug, Waves makes a cool one. You can widen the stereo image dramatically and play with the phase. it works well on certain things.
Another very handy tool is to double the SBD, flip the phase, add moderate compression (4:1), mess around with the eq and then add back to the main mix a bit to taste. This can work wonders to liven up stale material.
it's all about experimenting. Good luck. Phil