Wrapping architecture into contract, or having a separate architect?

[Michael Wolffs]

I've bought a property I need to get rehabbed.  Once I bought I immediately started contacting contractors for bids.  I got some, but some of them said the needed plans do do a good bid, and I needed an architect.  Some had their own, and offered to wrap that cost into the contract, basically being a one stop shop.  

But this got me thinking that I did the process a bit bassakwards, and should get my own architect, get the plans, rebid the actual construction work based on the plans, and then use the architect as part of the oversight of the construction (using someone who's arms length from the contractor.)

So which do you think would work best, letting the contractor front end the whole project, or having the architecture separate?