The Travis County Exposition Center is the location for the Republic of Texas Rally which attracts about 40K visitors. There is live music, bike show, celebrities, big rigs, vendors, and more that you can read on the ROT site. NOTE: the fee to get is $75 and there are no day passes. The temperature this time of year in Austin it is often in the high 90s or low 100s and about 90% of the event is outside so be ready in general and drink lots of water. A beer is $6!!!---so BYOB!
The Expo Center is about 20 minutes east from the party zone in downtown Austin which attracts about 200K people and there is no fee. Austin bills itself as the Live Music Capital of the World and 90% of the business on 6th Street and surrounding streets are bars. Downtown is blocked off for motorcycle only parking and for the party to flow into the streets.
The party in downtown Austin, other attractions downtown during the Republic of Texas Rally, the riding in the lush Austin area with a lot of park land and surrounding Hill Country; great restaurants and pubs, meeting up with old and new friends, and more is enough to fill the weekend.