[sarasi]

From Ogieshim's post it doesn't seem like he/she is planning on climbing it at all, just viewing it from Hakone or Kawaguchiko. Kawaguchiko has by far the more impressive view, but less to do if the mountain is covered in cloud (most of the time in summer, but if you have a reasonable chance of seeing it quite early in the morning in May. Just be aware that it is not always visible.)

The buses run to the 5th station (halfway point) from sometime in April (depends on the snow) and the shops will be open. I took the bus up in mid-April last year, and there was still knee-deep snow around the shops. Climbing to the summit at that time of the year is only for people experienced in climbing in ice and snow. The official climbing season is from early July to late August, when all the snow is gone.