By default 4e is only really suitable for status-quo sandboxing within a demi-Tier. I am trying to stretch it to a Tier using Threats To The Nentir Vale, by Minionising many of the standard mook monsters in the level 4-7 range, eg level 6 brigand standard becomes a level 6 brigand minion, these are the most useable across the Tier. But a level 1 standard monster like an Iron Circle trooper needs to become a level 6 minion if he's to stay useable across Heroic Tier.
With giving minions 1/4 hp too, so far this seems to be working really well - I can use the same level 6, 18-21 hit point minion now with PCs at level 2-3, and at level 6, and even at level 10 with enough of them & keeping PC magic gear in the 1-10 range.
Level 11+ it'll break down though, so that's when I plan to transition to a mix of Domain Level play and high level questing, I have King of the Trollhaunt Warrens for that.