Hi there I'm looking at building a room to tie me over until we move so in return can build my dream room, looking for some opinions and advise on a ideal room size and actual build, your thoughts are most appreciated. Typical basement with not so ideal

height restraints, floor space due to bad layout of stair location, furnace room, posts, beams etc.
Room sizeI have two space options see below:
(ceiling height is 9'3" from the bottom of floor joist to concrete slab, there are some steel beams with measurments of 8'7" from the bottom to concrete slab)
Option #1:
18' x 22'6" I have two 2" x 6" exterior exisiting walls attached to the poured foundation which will stay and I'll be building a new wall in front so to take this into consideration. I also have a furnace on the 22' end wall to contend with.
Option #2:
20' x 45' Going with this space I would have to relocate the furnace which would now be off to the side, currently it's 22ft into the 45ft space, I know I will not be using this entire space. I could now build both ends of the room further away from the exterior walls which have the 2" x 6" exisiting walls if I wish to. I would have only one exterior wall with exisitng 2" x 6" construction which would be staying and I would be building in front.
A freind provide a site
www.bobgolds.com to plug in measurements to look at the graph, he provided two measurements of 22' x 16' x 9' and 22' x 16' x 8'11" Looking at both of these what are your thoughts, I thought they looked pretty good.
The only problem being is I would like a wider room but plugging in such just messed up the graph.
My thoughts to date but not yet finalized;
Construction:
#1 Sub-floor: Installing first with walls built ontop, my thoughts are to use Barricade insulated subfloor
www.barricadesubfloor.com but another option is dri-core
www.dricore.com Which product do you think is the better to go with?
#2 Walls: Gasket installed under bottom plate onto sub-floor, constructing new 2" x 4" walls with double top plate in front of the two existing exterior 2" x 6" walls. All walls will be secured using RSIC-DC04 clips attached from the ceiling joist. The two new interior walls construction will be 2" x 6" top & bottom plates with staggered 2" x 4" stud construction, double top plate.
#3 Install material on the underside of the existing sub-floor, Roxel Safe & Sound will be installed in cavities and wall cavities.
#4 Preparation for drywall on the ceiling only: Use RSIC-1 Resilient Sound Isolation Clips with a furring channel (hat track) within or use a EXT04 clip which I would install on the side of the floor joist and be able to have my ceiling higher. This will depend on the actual ceiling height I want.
No preparation for walls, installing drywall onto the wood framing.
#5 Drywall installation: 2 layers of 5/8" with Green Glue between on the ceiling and walls.
#6 Green Glue used throughout between drywall and acoustic calking for joints etc.
#7 Acoustics: not yet finalized
#8 Soffits: Still wondering about these, I see some rooms with none, others with them all around the perimeter and some only down the sides.
Your thought’s in relation to this? What are the benefits or draw backs of doing such?
If I build these my thoughts are to completely finish the room so there is no room compromise and then build such, doing this then if I install lighting cans etc. I will have no concerns.
How would you construct these and what material would I use inside for isolation and for finish?
#9 Ceiling: Another thought is constructing a coffered ceiling effect so to break-up the waves, what are your thoughts of doing this?
How would I construct, material and how far down from the ceiling.
If I build these my thoughts are to completely finish the room so there is no room compromise and then build such.
#10 Bass traps: The two corners behind the speakers should I build these on a angle or just purchase so it’s more flexible? What are the benefits or draw backs from doing such?
If I was to build them how to do the construction, what isolation material do I use and finish?
#11 Bass trap, back wall of the room: It was recommended to build a cavity for such or should I just use mounted ones?
If I build one my thoughts are to completely finish the room so there is no room compromise and then build such.
How would you construct this and what material would I use inside for isolation and for finish?
What are the benefits or draw backs from doing such?
Thx