Mixing up cardio exercises, durations, and intensity...Give me some suggestions

I am getting ready to concentrate more on cardio. I am probably going to be doing cardio 4 days per week post workout. I plan to mix up the type of cardio I use by using these different exercises.
1) Stair Stepper
2) Treadmill(Jogging and running)
3) Bike
4) Elliptical Trainer

I was wanting to mix up how I do it by using one of the four to do long duration(45 min) low intensity, one of the four to do moderate duration(30 min) moderate intensity, one of the four to do 20 min HIIT, and one of the four to do short duration HIT. I am probably going to set it up like this.

Monday- Long Duration(45 min)Low Intensity
Tuesday- HIT(Similar to Guerilla Training)-Short Duration(12 minutes)
Thursday- Moderate Duration(30 min)Moderate Intensity
Friday- HIIT-20 minutes of Intervals, similar to BFL cardio sessions.

The long duration would be geared more towards endurance and a little fat loss, the moderate duration of 30min would be geared more toward cardio vascular health and slight endurance, the HIIT would be a combonation of endurance/cardio vascular/fat loss, and the HIT would be geared more toward high output of the body and speeding up of the metabolism. I just wanted to kindly hit a wide spectrum with this and see what happens. Now I get bored easily with the same ol' shit so I want to use these different exercises to liven it up. I am just not sure which exercise I want to use for the different style of cardio. Which one would you guys use for each day???

I was thinking Elliptical for the long duration, Stair Stepper for the HIT,
Bike for the moderate duration, and Treadmill for the HIIT.