I've run into exactly the same problem. I left a web design firm where I was an account exec, went out on my own, built teams and won some large scale contracts, and made great money with some great people.
(I took a 3yr hiatus to windsurf - reflected on what I wanted to do, and realized, I love coding - I want to stick with that - so I'm longer trying to build a bigger company and manage large teams (i.e. 6 or 7 consultants)).
So based on that, here is my suggestion on how you can approach this.
Most importantly, you have to begin by deciding why you are in this business and what type of freelance company you want to be - this is key because the more you scale up, the more you are in hands-on management and less involved in actual design and development.
1) If your first love is programming and design, then stick to that, build your company on personal attention to projects, your reputation and excellence. That means taking on less projects, but being much personally involved in both - everything you touch will be done to your standards - you can take a lot of pride and have a lot of satisfaction in that.
2) If you want to grow a company in size (number of consultants and projects), you are then switching hats to becoming great at managing people and clients.
My suggestion is to take some to reflect on what you want for yourself as a career.
If it's the first, take on less - do what you love to do.
If it's the second, then accept that you are now a team manager, project manager ad account executive at the same time.
Here is some helpful advice if you want to grow your team and clients and keep that growth sustainable:
1) I avoid taking on employees. My preference has always been to hire freelancers who have worked for companies, gained that experience, but then went out on their own. I've made exceptions for freelancers who have been highly recommended and demonstrated great attitude. I found the ideal is to be their biggest client, but not their only client. Don't overload them either - keep them hungry and available to scale up to take more work as you get more work.
2) It takes time to find the right people to work with (i.e. I've had to go through about 6 or 7 prospects before finally finding 1 good one). When trying somebody new, hope for the best and expect the worst - make sure you have a project with a long enough time line that if they don't work out, you can hire somebody else to fill the gap (this going to happen from time to time).
3) Here is how I price out my projects, protect myself, my clients and the freelancers from a financial perspective.
Handle the requirements phase - get this down pat. Your requirements need to be detailed so that everybody on the team knows the scope and specs they are building towards. Have provisions to handle 'scope creep' that are understood by all involved - and require a written change request and approved cost-estimates for those.
Break the project up into skills-sets required, then get the prospective freelancer to quote (tip: I add 10% to the contract for the freelancer to guarantee no cost overruns - they happily take the extra cash with no complaints)
Once I have all my costs added up, I double the price and request 50% upfront and 50% on 'substantial completion' of the project. The 50% covers my costs, so I know I can always pay my freelancers (important! - even if it's the clients who stiff you, the freelancers expect to get paid and you are responsible)
I give my freelancers a 50% deposit on their quote (that's half of your 50% deposit) on project commencement. I don't touch the rest of the client's deposit. It sits in a bank account until my Freelancers have delivered, at which my Freelancers get fully paid out. As far as I'm concerned, until all deliverables are met - I haven't earned a cent - it's more important to have that cash on reserve to pay your freelancers (or to hire somebody if one isn't delivering). You are fully responsible to the client for project completion - remember that.
When the project is completed, the client is invoiced, you get the second 50%, everybody's happy, your freelancers have gotten both a substantial deposit upfront and paid timely (pay them fast on completion and get them used to that - they will automatically prioritize your projects because they know they will get money quickly after completion!!!), the client has their project delivered, and you've made a good profit.
You will build a great team over time with this approach. Some freelancers will come and so will go. But you will build a core team that knows that they 'get clear specs, get a deposit and get paid in full' every time the work for you - and that's rare and sought after these days.
In the end, it is going to be your 'people skills' and your 'management skills' that will be your greatest assets - you've switched from designing and development to running a business and managing people and projects.
Expect it will be a rocky road at times - your challenge is to foresee potential risks and navigate those.
If it is excellence you seek, then be very careful in who you bring on - look at their past work - you'll see very quickly if they are the type of people who push out 'mediocrity' - or if they have that same 'gleam in their eye' for high-quality work.
Also, and I've saved this for last, because it is so important for dealing with people, and you brought up the loss of motivation.
I've found that, in the long-term, money is not much of a motivator to drive 'excellence' - you have to recognize it in people, compliment them on it and express appreciation - people thrive on validation and if you can give them that, it's like an addictive drug that keeps things challenging, fun and rewarding!!!
For those who work for you and excel, build up their confidence, tell them how much you appreciate having somebody on the team you can count on - make it a very rewarding experience for those who do great work.