I just had baby number 2 as well. My first son is 21 months. He had the opposite issue and decided that he was going to start not going to bed until about 10 at night and then not get up until about 10 in the morning. He started sleeping for 2-3 hours in the afternoon, and then a couple days ago, decided that naps were no longer necessary. This was a huge relief at first... but I talked to his doc at the 21 month appt and she said it is probably a reaction to the new baby. My second is generally laid back as well (though he does have an issue with colic-gas at times.) My first has become more attached to everything (especially me). He panicks everytime I pick up the new baby (particularly when it is to nurse him). He started throwing tantrums (that didn't get the results he wanted, so they didn't last that long), he started developing these suddden overwhelming needs when he saw me headed towards the swing to pick up baby brother. Most people told me that he would be totally used to the new baby within 2 weeks. This is just simply not the case. New baby is nearly 5 weeks old now, and it is getting worse. His doctor just told me that it doesn't matter how how laid back the new baby is... the fact that there is a new little life in the house that mom has to pay attention to is very earth-shattering to your first child, especially when they are so young that you can't explain or reason with them. Her advice was to just continue to do what you are doing in regards to loving your kid. If new behaviors are unacceptable, then don't accept them. With the sleep issue at night... we continued to put him to bed at 8:30... and if it took him until 10 or later to fall asleep, that was his issue. As far as the naps are concerned... yesterday, he wasn't asleep after being in his crib for 45 minutes, so I allowed him to get out, only resulting in his literally falling asleep during his dinner, and then extreme crankiness in the evening hours. So, my solution is going to be to follow docs advice on this too... put him down at the normal nap time and get him up when he normally gets up. If he doesn't sleep, it's still going to eventually be clear to him that this is the time to go down. She swears that he will even out. As opposed to yours, my first is extremely cuddly and wants me to actually be holding him for several hours a day. He has a very sensitive personality and I sometimes tiptoe around that sensitivity, and am really trying not to, because the last thing we need is a nearly 2-year-old controlling the atmosphere in the house.
I have really rambled here (from one sleep-deprived postpartum mom to another). The bottom line, try to have the schedule the way it was before your second was born, and your first should even out eventually. This is easier said than done, and I am only assuming that it will work. Will your first stay in his room by himself until regular get-up time? I am sure that lots will disagree with this, but it has worked for us to put a couple toys in the crib so that he has something to occupy himself. At first, I thought it would distract him from going to sleep, but it turns out that it just comforted him to have his familiar things around. Yes, he did play... but it was playing, not screaming, and that is always good. Good luck, and try to get at least 5 hours of sleep a day! (that, obviously, should be a much higher number!)