I visit Yosemite fairly often, at all times of year, and have a few comments.
First, late March & early April isn't really "winter". Spring is getting going. You won't have to worry too much about extreme-cold-weather equipment care. Though there might possibly be a little snowfall, it's more likely to be substantially above freezing. If you're lucky and late March is warm, the waterfalls may be getting going well (though usually May & June are much better). Because of that, I recommend bringing a very waterproof camera bag (maybe even enclosed in a plastic bag) to protect your equipment from spray on some of the trails, just in case (part of the trail to Vernal Falls is officially called "The Mist Trail", with good reason). If indeed the waterfalls are going pretty well, then they will be the most photogenic things in the valley (again, if you're lucky and the weather's been warm...). The trail to Vernal Falls & Nevada Falls is particularly breathtaking.
Other than that, it's hard to find bad views (except behind a bus!). Just wandering around the valley floor looking up at the cliffs is a fine thing to do. It's also obligatory for the first-time visitor to find the two standard picture-postcard locations: "Tunnel View" (see the official park map), and the road turnout right next to the river on the north side of the valley loop near the west end of the valley (which has a great view across the river and back east up the valley).
Also, if the Snow Creek Trail is in decent condition yet (talk to a ranger about its condition; there is supposedly some danger of landslides in spring, but I've done it partway in winter/spring anyway), there are great views of Half Dome and Quarter Domes across the valley, and it is particularly uncrowded (though steep).