[Gym at work] Limited equipment, looking for interval training.. what would you do?

I've found that having a gym at work and a fairly flexible job is doing wonders for being constant. However, it's fairly limited in terms of equipment. It does have a few benches, free weights, etc, but as far as cardio goes it has the following:

2 Ellipticals (one's broken and offers little resistance)
2 stationary bikes
2 "sitting/horizontal" stationary bikes (no idea what the proper name is)
1 stairmaster
2 treadmills with good incline range

My current routine needs to fit in an hour or so. I start off with 10 minutes of stairs (alternating resistance in 40 sec. intervals, trying to mimic the "sprint/rest" of interval training) and 10 minutes of elliptical (highest resistance possible, 1 minute sprint/1 minute slow). I then follow up with roughly 20 minutes of free weights, benchs, situps/crunches and squats in some sort of homemade circuit style (i.e. no rest between stations, 1 minute on a bike between circuits). Leaves me about 20 minutes to cool down and shower. I do this 4x a week.

I've lost a ton of weight (which was my initial goal about a year and a half ago) and my cardio is getting pretty damn decent. On a exertion scale of 1-10 I'd say I'm at 7-8 when I "sprint" during my cardio portion. That being said, I don't want to start plateauing. I feel like I still can lose quite a few pounds before I start looking seriously at my diet.

Questions:

1) Should I start with strenght training circuits first and then finish with cardio? Sandwich it between the two 10 minute segments? Should I simply do 1 day cardio/1 day strenght and not mix the two?

2) Out of the cardio machines I've listed, which ones would you go for?

3) Is Interval correct? I've started relatively recently (2-3 months) and I had been doing the same boring stable thing before that (i.e. no change in rhythm or exertion rate).

4) Is circuit-style the best for weight loss? I'm not looking to bulk up much, I'm already a pretty big guy muscle-wise (thank god for genetics), I'm looking for more muscle definition, etc.

Any other recommendations would be appreciated!

Can you not get a regular gym membership?

Like I said, I can fit my gym whenever I got a free hour at work. I know myself, and if I had to do it before or after work, I'd probably find any excuse to skip it. As it stands, I got my gym bag at my desk and whenever I want I can go train. It's just incredibly convenient.

if you're not dedicated enough to do it consistently, it doesn't matter what you do or don't do, so do whatever you want...it will all be equally ineffective

Go outside and run. Best HIIT there is.

You can do cardi oand strength on the same day, just not during the same workout.

Well, in terms of which of those machines I'd prefer ... I think I'd go treadmill as soon as you can handle it and do sprint/jog intervals there. Your intervals look fine. If you're worried about plateauing, just decrease your rest intervals or lengthen your sprint intervals as necessary.

Go outside and run. Best HIIT there is.

You can do cardi oand strength on the same day, just not during the same workout.

truth

you can do a form of interval training with any type of cardio but you'll get the most out of running. i do intervals on an elliptical at my work's gym and while it's a decent workout it isn't the same as real running