Hi Nicole,
I have no good advice for you, but I'm in the same boat...My DD2 is 9 weeks old and although she sleeps well at night, she has a tough time napping during the day. We also have a 3 y.o. DD, so like you said, it's hard to get the time to do the "routine". I absolutely loved the Baby Whisperer book and think that you'll find a LOT of useful info in there. I'm also reading Baby Wise, which is similar and liking it as well. First thing would be to get a good schedule going so everyone, including baby, know what to expect. Then, a lot of things fall into place by themselves. As for how to get them to nap better - I'm up for suggestions, too!! I think our problem may be that she is getting overstimulated/overtired...So we're going to try to watch her sleepy cues better and possibly put her down for naps sooner. We'll see. Good luck with it - you (and Tyler) will do great!
Mary