Sometimes you have to say "This is how it is"

Then your  job is still to get people to buy into it.  If you have a vision and feel strongly about it, democracy and group decision making are probably not the way to go.  Take your vision and run with it without wasting a lot of time in a process which dilutes your vision and renders something "less good."

Just tell your team that you have thought about it, developed and weighed alternatives to come up with the plan and here it is.  You have to be sure they understand that if you have overlooked something or made a serious error they can speak up .... and that you want them to speak out forcefully.  [See my post "Don't surround yourself with people who demand too little of you"]  You may (should) choose to leave details of varying degrees to be "fleshed out" before final implementation.

Sound too autocratic?  That's why you make the big bucks.  Look at a football coach; he is in charge of the game plan.  Some rely more heavily than others on their offensive and defensive coordinators to develop their plans, but you can bet the head coach puts together the basic plan.

Note: At other times group input to a decision, plan, procedure, or design is to be encouraged and has great value, but sometimes you have to say "this is it" without input.  At other times, if there is not a concensus, or the process is taking too long, it is again your job to say "THIS IS IT!"

A long and potentially boring example follows.  You may want to quit here. 

At least 15 years ago, it was apparent that we needed a new accounting software system.  We were still using a "DOS based" system (information for those who have a computer history going back before about 1990, when Windows 3 was released).  I believed strongly that we should adopt a Microsoft Access based system that could be migrated to a SQL based system.  Others believed we should buy a packaged system which, in my view, would have us caught in the clutches of the vendor we chose forever.  An Access based system would be more "open" and easily customizable.  I left no choice.  We went with Access, going "live" on July 1, 2000.  Now we have 12 years of data accumulated that anyone in the organization can probe to find answers to their questions.  And some do.  Though most in the organization choose not to create necessary queries and reports, the data is there and quite easily accessible.  Just this week I created a detailed 12 year sales history for a particular product line so we can implement a new marketing strategy for that product.  A couple others on the management team have done similar projects.