This weekend is the 21st annual Memorial Weekend in the Wine Country.
Most wineries are open and there's no better way to visit than by bike! (Most of the wineries do have a tasting fee, but often refund it with a wine purchase.)
The south end of the Eola Hills are picturesque and offer a good number of wineries.
There's also a bunch of wineries in the Waldo Hills and out south towards Ankeny. For a short-hop, Willamette Valley Vineyards is probably the closest to downtown Salem.