You will have easy access along the Texas Coast in April. Snow birders have left and summer crowds haven't shown up yet. The Rockport to Port Aransas area was hit hard by the hurricane although many businesses/restaurants have reopened. Goose Island State Park is close to opening and Mustang Island SP is still closed. April is a great month to visit the coast and if you are going further west then you should consider Big Bend NP and West Texas. Also April is bird migration month and if you are into birding there are some great places.