There was a thread about this on the Corporate Forum about a month ago. Let me clear this stuff up about the Citation, because there seems to be a lot of confusion about it.
1. A Citation II (C550) is a TWO pilot airplane. An approprialtly rated SIC (65.55 checkout) can log all the time he is on that airplane as SIC. He can log this time whether it be flown under 91, 135, or 121 (obviously needs 135, or 121 checkrides to fly it under 135, 121). Also there are no Citations being flown under 121 for those nitpicks, just used as an example
2. The fact that the PIC has a single pilot waiver, makes no difference, because a C550 is TYPE certified as TWO PILOTS. The PIC is simply not using his waiver.
3. You can not log PIC time in a Citation unless you have a type rating (CE500), this is not a King Air (type rating not required) and sole manipulator does not work!
4. A C501 or C551 Citation (Citation ISP or IISP) is different and this is what confuses most of the people on the board. Since the airplane TYPE certificate states two pilots OR 1 pilot.
5. You do not need to go to FS or Simuflite to get a 61.55 checkout, any PIC can give a 61.55 checkout. You just need to go out with no passengers and daytime and to the manuevers required by 61.55. The PIC does not need an ATP or MEI to give this "checkout", and you can log all of this time as SIC according to 61.55F.
6. There are some Citations out there (I personaly know of a C560, and a C525) being operated Single Pilot and 135. While this is not common, since the hurdles are large (insurance and an understanding FSDO), it is possible.
7. My copilots have had no problem getting hired on by the regionals with SIC jet time and little PIC time (2 Skywest, 1 Coex). MAJORs are the ones that want the PIC turbine time.
8. If you read the board long enough, when a thread like this comes up, most people will say that they're experience (college, 141 school, fractional, regional) is the best way to go. I disagree with all of them, I believe what YOU make out of it is the key here. Flying as an SIC is what you make out of it. You CAN learn a whole lot by constantly flying with EFIS, TCAS, EGPWS, INS's, SID's, STAR's, shooting real approaches to airports you have never been to, basically just getting to know how the system works. However, if all you get out of it is learning how to put coffee and ice on the airplane, that 1000 hours SIC time is as worthless as the 1000 hour PIC that has never left the local training environment.
Congradulations on the offers and good luck!