I sat in row 21 for one of the many Angels games last season. The view was spectacular. 39 gives you the luxury of being close to both the outfield and the infield. There are 40 rows total so the closer the better but even in row 40, your view is great but it's always better to be closer to the field. Especially if there is a right fielder you are particularly fond of.

The only thing I disliked about my seats was the placement of the scoreboard. It's no where near as big as the other jumbo displays I've seen in other ballparks. Plus it's at the extreme top of the ballpark, on top of the home run porch even. If you sit in 39, you will have a poor view of the scoreboard so if you're a Rangers fan constantly looking at the stats and lineup, you may want to opt for a section closer to the infield and dugout.