Red Mountain is a rugged, nearly treeless rise set amid the green valley of the Yakima River. It's one of Washington's warmest growing regions and home to some of the state's best vineyards and wineries. The sparse beauty here has always drawn me to this place making it one of my favorite places to bring tour groups. One could spend an entire day visiting the wineries on Red Mountain and it's ideal for small and large groups alike. There are premium small-production wineries perfect for smaller groups as well as larger wineries with event space and catering services.
There are not many accommodations on Red Mountain, rather plan to stay in the Tri-Cities where you will find a better selection of restaurants and hotels. I recommend bringing in your own picnic or catered lunch and plop down at one of the wineries with a picnic or event area. Obviously with large groups planning lunch on a winery grounds needs to be pre-planned and may incur additional charges.