The cheapest tickets at Wrigley Field are usually found in the Bleachers or in the 400 and 500 Levels. While the 400 and 500 levels are located on the same seating deck, there is a significant difference between the two seating areas.
The 500 Level is Covered But Only About Half of the 400 Level is Protected
The roof at Wrigley Field is fairly substantial and keeps all 500 level sections fully covered. On a hot day in July or August, being covered can be the difference between sweating out your Old Style vs. enjoying it comfortably. The same goes for the rainy part of the year in April and May. This is when fans in the 100 level wish they would have saved money and bought in the top deck.
While the 500 level is fully covered, you're not out of luck in the 400 level. In fact, most fans don't know that roughly 50% of the seats are actually covered. If the rain isn't blowing, you can comfortably sit in row 4 of a 400 level section and be dry.
If covered or shaded seating is your top priority, be sure to check out the Wrigley Shade and Cover Finder.
Being Covered Also Means...Poles
The 500 sections have a cheaper price and they're fully covered - snatch those seats up, right? Not so fast. Something has to keep those seats covered. And it's the roof. And something has to hold that roof up. And, (gulp) it's a set of annoying poles perfectly placed to block your view.
Everyone's worst nightmare at Wrigley (and Fenway) is being stuck behind a pole. If you have a seat in a 400 section, that's something you don't have to worry about. But if you have a seat in the 500 level, you'll be playing roulette. It's the ultimate trade-off at Wrigley Field: you want to be covered (or want a cheap ticket), but it usually comes with a set of risk.
So What's the Best Balance of Value and Overall Experience?
This answer is pretty easy. Rows 8-10 in 400 sections offer the best combination of quality view + cover + accessibility. You never have to worry about obstructions and rain and you're just a few steps away from the walkway shared by the 400 and 500 levels. These seats will also save you money over the front rows of the 400 sections (which have a very good view and should be considered on days when rain or sun are not an issue).