Guardians of the Orb - Idea

I'm going to start this off with a small encounter idea. I have 2 PC's, so this has to be a slightly scaled down encounter. It's meant to be a fun, fairly easy encounter where the PC's have to use some strategy but they get to kill a lot of monsters quickly.

Story:

The PC's are sent to recover a magical item called the Eye of Ioun. You could replace the Orb with any magical item that fits your story. The Orb is guarded by a couple of guardians that attempt to stop the PC's from touching the orb. The concept is that these are large golemn like stone guardians, most likely soldiers.

Once the PC's touch the Orb four hidden doors slide open and they are mobbed by a wave of minions that try to stop the PC's from leaving with the Orb.

To help make the minions easier to take out the room will have a couple of crystalline "blasters" that will allow the PC's to send out a blast to take out the minions en mass.

So, there is the basic idea, I've sketched up a map which I'll upload in part 2. Do you have any ideas, tips for making this encounter good/better, any suggestions for monsters to use?

Introduction

My story is unremarkable and probably very common. In middle school I learned to play D&D from my friend, who learned from his Dad. We played 2nd Edition in his basement after school and on weekends.
In college I found some friends who weren't weird, also enjoyed D&D (which can sometimes be a hard combo to find) and we played 3rd Edition. Members have joined and left the group and now we are adults with jobs and families and we play 4th Edition once a week.
I have DM'd off and on from 2nd Edition until now and enjoy it. One thing that really changed with 4th Edition (and it's been talked about to death) is encounter design. It used to be okay to have a good story, scatter it with fights and dungeons and throw in a couple memorable fights (the boss who throws PC's through the dilapidated buildings of an old ranger village, or a fight on a stone bridge over a volcano). Nowadays however the encounters have to become part of the story, it is more critical to have each battle be a puzzle on top of a location with monsters mixed in. A good encounter has to be a key action sequence in a movie that keeps the players on the edge of their seats while moving the story forward.
How does 1 DM accomplish this? Movies have teams of writers, directors, producers, special effects wizards, and cinematographers to help make a film feel epic. But how do you, sitting at a table with a stack of books and a laptop make an action sequence that feels like a scene out of a summer blockbuster?
Then comes the idea for this blog. There are so many great resources for RPGs and D&D in particular that we hope this blog will be added to the list. While many other blogs focus on D&D rules or DM tips, in my opinion there is a shortage of good encounter resources. With Open Encounter Design we hope to take the idea of an Open Source community and apply it to encounter design.
To start on this excursion I'll be posting some of the encounters I've run for my group and present them to the community along with what worked and what didn't. Then using feedback we will make the encounters better so that you can use them.
Let's see where we go...