Depends on where you are planning on working while you are in town. Off the top of my head, Umeda has a Hilton and Ritz Carlton in Umeda which is the business district in Osaka. Along with those two hotels there are numerous Japanese business hotels in the area. From Umeda you can take the Hankyu train line and head towards Kyoto. Just recently in Kyoto the new Hyatt has opened up near Kyoto station.

Please elaborate more on where you plan on staying while you are in town, is there an area where you are going to need to be more often?