Well I have an 8inch Dobsonian Newtonian Reflector, and with my highest power, mars will fill my view.
Mars has always been visible with the naked eye. In fact, its visible right now. it just looks like a little orange dot tho with the naked eye
because the object in question is within the solar system and is pretty damn big, you could use any scope. department store crap to a observatory quality telescope and it'll look decent. Binoculars would be great for this too.
of course the more power you have, the bigger it'll look. I dont know the multiplying factor that would be good...I'm not going to ramble on about that because its different for different scopes. if you could get something thats even like 40x or more, it'll be small but you'll see detail... you could go 1000x and it'll be huge, but it'll just look like a fuzzy red ball unless you have a 16 inch wide scope!
Also, if you have access to a red color filter for your eyepiece, that will bring out the details on the martian surface aswell.
I love astronomy. if anyone else out there is remotely interested in space, astronomy, astrophysics etc, check out
www.space.com ,
www.rednova.com , theres another great one I'm forgetting right now but i'll post later. EDIT: its
www.physlink.com
Also a reality check... Mars will be closer than it has ever been in the past 70000 years or whatever... if you think about it however, this is only statistically significant, since next time around it may be 1/2 million miles farther away... that really makes no difference when we're looking at it from earth with our amateur telescopes. so really, going out today and looking at mars will look nearly exactly the same as when you look at it on August 27th.
This also happened a couple years ago with Jupiter... hyped up on CNN and what not and it looked no different than it ever had. Not to say that this August 27th wont be a great day to see Mars, I'm just pointing out the fact that it's not going to look a whole lot different!
Ok I'm taking my geek glasses off now. go out and enjoy the night sky!