Question about Rome

I'm doing the Euro Explorer in April 09 and have a wish list of things I'd like to do in Rome...but I have no idea if I'm kidding myself about fitting all of these things in.

On this tour, Rome is a 2 night stay - and I guess this probably means arriving in the evening and then a morning departure.

Anyone who has been on this tour, or one similar, I'd appreciate it if you could let me know my chances of seeing (and exploring):

*Sistene Chapel
*Colosseum (I know I can take an optional for this - but I don't know if doing so will use up all of my free time, making it impossible to see much else)
*Pantheon
*Trevi Fountain (I realise this probably won't be a problem)
*Bocca Della Verita

I think that just about covers it,

Thanks in advance!