Definitely the suspension, and seat, could do with improvement.
The good news is that there's fine weather protection and 55ltr space under the seat. Add on a Topcase, or a trailer, and you can carry more luggage:
Google for Images with the "Suzuki Burgman and trailer" search term. I've been slack and havn't yet uploaded my webpage & pics to my present ISP, but two versions of my own trailer are on show through Google itself --- just don't try to go to the source at this stage.
(NB. I now have a Topcase and my trailer is awaiting its next make-over.)
'77 BMW R100RS with Ural chair
'08 Suzuki AN650A Burgman (and trailer)