transfrom office from corporate to startup

Briefing

We're a small tech startup, currently with 4 people in the office and expecting to grow to 5-6 in this office. The office space we're leasing looks rather corporate and doesn't reflect our startup vibe. The layout is set up as 4 private offices with doors all opening into one common area. I'd like the office to feel more connected - as opposed to 4 separate rooms leading into an unused common area.
* Office 1 is the GM's office. It should remain as such. It needs to incorporate a layout and feel that enables 2-3 people to comfortably work collaboratively with the GM when needed.
* Office 2 is the only other office with exterior windows. The desks can be moved, but unfortunately the wall cabinets are fixed in place
* Office 3 has no permanent fixtures. The layout shows this room to be rectangular, however one of the back corners is actually not square - you can see in the photos what I mean.
* Office 4 also has fixed wall cabinets
* One of the offices #2,3,or 4 should be a collaborative working space / conference room. I was thinking #3 because it has more wall space for a TV display and white boards, but I'm open to suggestions. Where ever the conference room is located, it will need space for a 50-inch TV to be mounted to the wall. The TV is used for working collaboratively and also for skype video calls with our office in Israel. The 'conference room' will be used almost exclusively for internal work sessions/meetings and adhoc collaborative working. It will rarely need to be used to host customers or other 'formal' activities.
* Three of the employees (2 salespeople and the GM) spend a decent amount of time on the phone. The salespeople need working spaces to comfortably make these phone calls without worrying about disrupting their co-workers' work environment or talking over each other when they're both on calls at the same time.
* I'd like seating options to allow for chilling out. Options for something other than an office chair to sit on.

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