I agree, turning a large balcony area into another theatre or two has the best chance of being done right. That leaves the main auditorium with the big screen, and usually helps by moving its projection room downstairs with much less keystone distortion than from way up above the old balcony. With care, you can still have a very good large auditorium and a nicely done smaller screen or two as the pictures play out. The trick is in paying attention to the details: good sightlines, good acoustic isolation, new seats with lots of legroom, maintaining the character of the older building, etc.

You must make sure that the ceiling in the rear auditorium is completely soundproofed
and the hangers fastening the ceiling to the bar joist clear the projection beam.

The main disadvantage to having a short throw with the original wide screen is the poor depth of focus of the really short focal length lenses required.

For example, let's say the original theatre had a 120 foot throw to a 25x60 foot screen. The "scope" lens would have been about 85 mm, and the 1.85:1 "flat" lens would be about 55 mm. Now put a wall across that wide auditorium. A 60 foot throw to the same large screen would require a 42 mm "scope" prime, and something close to 27 mm for "flat". With the 6000 watts needed to light even a moderate gain curved screen of that size, the heat-related "focus flutter" will probably be beyond the ability of those short lenses to hold focus well.

A few minutes trying various options with Schneider's Theatre Design Pro software will make the tradeoffs clear:
http://www.schneideroptics.com/theatre/desprodn.html

IscoOptic's free Cinema Lens Selector Software will tell the same story:
http://www.iscooptic.de/english.html

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Century HAS split some of their domes... I assume you're talking about those in Sacramento. But they have some GREAT examples of preserving the large screens. Let us not forget the Century Complex 5 in Pleasant Hill, where they created a 2nd lobby and wrapped 4 new screens around the original large dome.

I would divide it like you would cut a pie into eight slices. Using two of the slices as an entry way to the center core. The entry way to all auditoriums would be around the core. The Booth would be above the core with the screen curved to match the outer perimiter of the exterior walls.

The reason I am using two slices for the entry way is to give you enough room for Concession, restrooms, game room,boxoffice,
crowd control for your 6 screen complex.

A circular or polygon design with slice-shaped auditoriums and a central "core" is attractive. I would go a step further and have an exit hall between each auditorium in the "slices", to provide better sound isolation between auditoriums, and exits at the sides of each auditorium. The design has the advantage of a single compact projection room located over the central "core" lobby. It provides a large front wall for the screen, with the wedge-shaped auditorium putting most seats in the front half of the theatre, but allowing a longer throw to aid focus. The concept could be used for both stadium or conventional sloped floor designs, but I would prefer the latter.

AFAIK, doesn't Famous Players (Canada) use a circular/spiral design in some of their new theatres ?