I suggest that yall don't hesitate to head for the bus as early as possible ( your Luggage will go under the Bus in the Luggage bins) and snag a couple of good seats ( stay out of the Suicide Seats in the first Row)after boarding.
Last fall after the San Diego Gathering we had to do a Bus to Train transfer, so we got to the Santa Fe Station early( the Buses load on the Street outside the Station)and lined up by the bus.
By the time the Driver started boarding us, there were more people than seats available, so the folks in the back of the Line had to wait on a Second Bus to arrive.( the Bus was fairly New and comfortable)
The trip up 101 went smoothly, and we arrived into Irvine right on time,( the Station was very crowded with all Inside seating full) claimed our bags, and headed to the Platform, which was across a Bridge over the Tracks, ( there is an Elevator if you can't do the Stairs) and waited about 20 minutes for our Train to arrive, jumped onto the Train and rolled into LAX right on time.