also, i am about 5'11" so I suspect a straight shaft is best?

I believe Echo for the dollar offer the Best Product . Stihl have very good units alo but have a much higher price tag . I have worked on both Manufactuers and they both are rather user friendly with little down time . I still have 3 Weed-eaters that I still use (over 20 yrs) but they are much more tempermental and are much harder to find repair parts for . Fortunately I have more than enough doaner (spares) . Honda also provides a quality unit , but again at elevated pricing .

Thanks, would I be ok with any of the Echos at say HomeDepot, or is there a certain model I should look for?

I would go to a Dealer so you can have any questions answered properly . The GT-225 goes for around $150.00 with a curved shaft . The SRM-225 lists for just around $200.00 . Both Models have a 5 yr residental / consumer warranty .

How much to you have to cut? If it's a normal residential lot an electric unit will work well.

I have used Echo and Stihl and liked them both. I do like my straight shaft though, and think it might be worth some extra money depending on how much you use it.

If you plan to edge your walks straight shaft makes that easier as well.

Your yard size will determine the equipment, and the cost. Probably top-of the line.
Needless to say, stay away from Walmart.
Make friends, if possible with a good lawn.garden equipment place....much better service than the box super stores.

I had a chance to put my hands on about every new trimmer there is a a home and garden show last weekend. The Echo and Stihl are both solid units. I had never seen a "pro" electric trimmer, but got a chance to run a CORE trimmer. The owner was at the show and was from Montana. A product made in the good old USA - that's a change! I was really impressed with the power and it is priced comparably with gas products. It is worth a look if you have a local dealer.

Here is a link that might be useful: CORE Trimmer