[lazor]

Depending on how much diffusion you want there are a couple of different diffusions by Rosco that I use.
R101 just takes the hardness off the edges but you can still see a defined spot
R132 takes just a little bit more
R114 I use this when I really need things to blend, not sure I would use it in a spotlight

I stick to Rosco diffusion usually and for your case I would recommend the R101 or the R132.

As mentioned above, I would also not recommend the baggy technique.