VCT was my bread and butter for quite a few years. As far as bidding goes, take two things into account: the job its self and the square footage.
The Job Its Self: That means how many hours would it take one person to do the floor (total manhours) x your price per hour + cost of materials and general overhead. Total manhours means if it takes one person 20 hours to do a floor it will take 4 people 5 hours to do the same floor. Cost per hour you want to remember that you will have a crew with you that you'll be paying- how much do you want to pay them and how much do you want to make for yourself on each of THEIR hours. Cost of materials is just how much the finish and stripper will cost + how much of your insurance, fuel, equipment maintenance etc do want this job to cover.
Square footage is pretty straightforward- you measure how many feet long by how many feet wide and multiple these together, so a 100 by 100 foot floor is a ten thousand square foot floor. Now you put a price per square foot. That can depend on so much and really is something you have to come up on your own though generally speaking .20-.60 is a normal range for a strip-wax. Large retail is normally on the lower end of that and high-end smaller areas are normally on the higher end of that.
Floor work is by no means dead- but you have to aggressively, constantly, be seeking new accounts. In my area at least you have a mix of big chain stores and small locally owned chains as far as retail goes. When I was doing it, we had 70 drug stores on a single chain as subcontractors, 3 locally owned large supermarkets and a a huge amount of odd ball doctors offices, schools, offices. To me, that is how you have to do it-have a mixed client base.
The big chain we were doing paid $80. per regular service (gum scrape/dustmop/machine scrub/propane burnish/dustmop again), and took on average an hour for one person to do one store. $80. isn't "much" for the quality we were giving them, but honestly we made out like bandits. We paid the employee a salary of $25.00 per store, $10.00 went to overhead which left us with a profit of $45.00. $45.00 x 70 stores a week was $3,150 in profit for us. Greedy? No way. $20.00 an hour is excellent pay.
I made a point to personally supervise all of the stripping and waxing services, which were a loss-leader for the chains but which I made out on the grocery stores. 20,000 SF x .20 per sf = $4,000. $600 in materials and I paid my crew of 8 a hundred dollars flat for the job, so that is $800 + $600 = $1,400, plus about $200 for miscellaneous overhead for a grand total of $1,600 cost to me. But I made $3,400 for 6 hours work. Again, was that greedy? No way. $100 for 6 hours work for my guys, plus buying them cigarettes, paying for everyone's lunch etc.
I loved doing floors, everything about doing floors. The problem with retail though is that they often have shop-lifting issues so they will rarely give you the keys and let you come in when you want overnight. Which means services have to be done either right after they close or right after they open. That is another reason to have a good mix of clients. If you have a ton of offices (etc) that you are doing the floors for, you usually get the keys or can arrange to be there when the office cleaning company that has subcontracted you is there cleaning. So the best program really is to have some retail that you can do at the start and at the end of the night and a bunch of non-retail that you can do between the two.
Honestly, in my opinion, you want to be diverse and grab up as much general janitorial as you can so you are cleaning the offices between doing floors. Two services a day, even top-rate, don't pay for a truck, a large walk-behind scrubber, and a 27" propane burnisher, all of which you should have if you plan on doing the big stores.