For affordability, access to the concourse, a great view, and protection from the sun, consider sections 126-129. You will save a ton of cash vs. the lettered sections right in front of you, while enjoying a more panoramic view of everything Chase Field has to offer. The sun will not be too much of a factor in early April, but it will be at your back if you sit down the third base line. These seats also give you a decent chance at a foul ball, are located behind the D-Backs dugout, and will have a coveted infield view.

View from Section 127 at Chase Field
Sections 126-129 offer a great overall experience without the expensive price tag of Field Level seats