I'm at that In-Between place again: finished one book, haven't started another.
The IBP is an interesting mind-set for me, because it lets me get caught up on all the other little chores I've put aside -- sorting through a file drawer, arranging for promo, rearranging things, planning the garden...
I've found that it's no good to push myself to start the next book. I'll start it when I'm ready, when I feel like the characters are solidly in my mind and the plot is percolating. That's what's happening now -- the percolation is bubbling along nicely. I have some of the scenes firmly in mind and I've jotted them down and I have a few other scenes I'd like to work in, but am not sure they'd be appropriate. I've got a good sense of the time of year, the location (although I'm waffling a bit on that), and other details.
This is where a good road trip comes in handy. I use the time I'm driving as a chance to sort through a lot of ideas in my head. And I just had a road trip last weekend, so I had a chance to think about some of these details, adding to the percolation factor.
I imagine I'll be jotting some more for another week or so, then the need to start Real Writing will take over and I'll dig in. Until then, I'm enjoying the In-Betweens.