Let me preface this by saying, I love Long Fights (as outlined in the Dungeon Master's Guide 2).
But the reason why I love long fights is because they're harder. The fact that long fights can exist-even long fights comprised of Level +4 encounter segments-means that encounters can be increased in difficulty to begin with.
It's my general philosophy to steal a play from... actually I'm not sure who used it first. My DM used it in one campaign, after I had already thought of the idea, but I don't remember whether or not I had told him the idea when I first thought of it, and there's no way of telling who came up with it first. But anyway, the idea is simple-if a Solo Boss isn't threatening enough, make the party fight him back to back.
In short, a solo monster can be treated as two phases of a Long Fight. Upon "bloodying" the creature, the party regains encounter powers or can spend healing surges as per normal, and then phase two begins. Effectively, you have one creature with double the hit points, whose actual combat strategy can change completely between the phases. From a roleplaying standpoint, whever you're fighting just hot a whole lot tougher-like +4 level t ougher!-but the game is actually managable.
But again, it goes to show that the basic premise this blog takes-that without "widget items" 4E combat is balanced-is potentially flawed to begin with. Long Fights are winnable because normal fights aren't razors edge margins of victory. But if you throw nothing but long fights at players, it gets old fast.
But I suppose not every encounter has to be a death defying moment to begin with