Todd,
I have not flown IFR into Kissimmee but do fly into KSFB from down the East coast on a regular basis. I can tell you they like an approach into the MCO class B from a gate to the East. They will always re-route me over OMN and at even altitudes. They use CORLL One arrival for me. For KISM I believe they will use BITHO One. They will probably not tell you they are putting you on the arrival but it will involve the same OMN, fixes and Low altitude. They will want you low after OMN. Count on using V3 or V437 traveling South. As a single engine I will usually decline V437 but will take V1-V3.
Have a good time at Disney.