reason is fantastic (for what it is, a software synth), and with AA 1.5, you can sync the two together using ReWire - it comes with reason 2 and 2.5, but i'm not sure about Adapted.
i've got lag when i do it, apparently AA doesn't have ASIO drivers yet, but that's ok. reason will let you program and number of drum and synthesizer tracks ... strings, bass, FX, it's an extremely powerful tool for us home musicians.
to sync Reason with AA 1.5, open audition, select a track, go to 'options' - 'device properties' - click the checkbox to enable reason, click the radio button for summed stereo output (should be the default), click launch. reason should launch in slave mode ... the controls from audition should control reason, the bars and beats should also be in sync ... have fun!
on my pc, i get a two note lag when reason is running ReWired, so i just start them up separately, loop audition, and hit 'play' in reason when audition comes back around to 1:1:00. it's a crappy workaround, but it's better than nothing.
good luck.
--edit--
also, you can use your midi keyboard to control reason ... i don't have one yet, but my friend does, and he's made some amazing stuff ... someone here should be able to give you some more in depth info.