system packages don't really vary in size - they are always the same size because they are the whole OS installer. so the system package sizes are the size of the install discs - windows may be ~700megs, solaris 10 might be 2gigs, i have no idea for AIX or HPUX. RedHat and SLES are about 2-3 Gigs each.
an oracle package might be a gig. the symantec client would be like 30 megs. winzip is like 1 meg. weblogic might be 30-40 megs. our packages are no bigger than the software we are installing.
so again - it all depends.
remember that in some cases we can use the 'network deploy' and we leave the installers on a pre-existing file share (outside the bladelogic depot) and we may not even need to copy to the target server.