Sectionals are the best! Some tips for you on using them:
-Wear firm soled shoes. The round rungs can start to hurt after a couple hours.
-Buy a "base section " and get the levelers. You'll be glad you did.
-Rub a candle on the area where the ladders slide together. This helps with disassembly.
-Buy a slip cover for the top. It prevents damage to window trim/walls.

Yes, they are expensive and so is the shipping to get them, but once you use them, you'll swear by them!