Using a wedding venue that provides catering is an one way to make it a little easier to manage your budget. And there are several venues that are gorgeous and have great food. A few we have worked with are The Terrace Club, Chateau Bellevue, and Thurman's Mansion at the Salt Lick. These venues also provide the majority of your table rentals, (go for the chair upgrades), basic linens, staff, and even centerpieces at The Salt Lick.
Most venues that do not provide on-site catering have a recommended or approved catering list. These are usually folks with whom the venue has worked, and they know the caterers can easily set-up and provide great service. Many of these venues do not have full kitchens, so you will want a caterer who can bring everything they need on-site.
For private parties, there is a lot more flexibility with catering options, and the choices can be overwhelming. Just about every restaurant in Austin offers levels of catering. It is important to ask if they provide staff to help serve so your guests aren't responsible for set-up. If you are open to a more non-traditional option, reach out to one of Austin's many food trailers to ask for catering for your next event.