It doesn't sound like you ran with the monster creation rules from 4e, but rather used something like a mix of monster/PC creation. Looking at solo monsters in 4e, they usually have powers with recharge mechanics, recharge at bloodied and reactions. (Assuming you used a solo monsters as the monster lasted up to 10 rounds...)
Another note is that the damage in early 4e was too low, if you had used the current revision of the rules, that fight probably wouldn't last more than 4-6 rounds making the amount of rince-and-repeat much lower.
Just take a look at the dragon at page 112 in Monster Vault: Threats to Nentir Vale and you will see what I mean. It's a skirmisher that never stands still, with a multitude of ways to move around and attack.
Right the monsters had recharge powers, but most of the time they recharge on a 5 & 6 or just a 6. So, a 1 in 3 chance or 1 in 6 chance of recharge. And, since I had a big group, I would put a solo on the board, as well as an elite or two and a few others.
But, for the final encounter, I used a modified version of Baba Yaga. Level 27 Solo Controller with 984 hit points.
Round 1: Vile Transmutation as Standard Action, Sweep the Field as a Move, Evil Eye as a Minor... Action Point to use Crushing Grasp (recharges Vile Transmutation)
Round 2: Roll to recharge Crushing Grasp (no) Vile Transmutation as Standard, Sweep the Field as a Move, Evil Eye as a Minor, Action Point to use Broomstick (recharges Vile Transmutation)
(remember, at this point, most of the PCs have something that grants them additional or bonus saves, or they can grant allies a bonus save...)
Round 3: roll to recharge Crushing Grasp (no) Vile Transmutation as Standard, Sweep the Field as a Move, Evil Eye as a Minor...
Round 4: roll to recharge Crushing Grasp (yes), which she uses as a standard, Sweep the Field as a Move, Evil Eye as a Minor...
And, then for the next umpteen rounds, I was doing that same process over & over again. Because of her aura, several PCs stayed outside the range for Evil Eye, Vile Transmutation, Crushing Grasp, etc. When the PCs finally bloodied her after like 10 rounds, I declared the battle over since all the PCs were basically at full hit points, just down action points and most of their dailies from taking out the elites and others, and now the archer ranger could turn his attention to her. (the main damage dealers in the party were occupied by the elites, while the lockdown defender kept being subjected to the Vile Transmutation and being turned into a toad.)