Although I have no comment on the layout of your trip or the cost, I can say that it is not at all difficult or expensive to travel on your own in Guatemala. I was there for 8 weeks last year and got most of my advise right here and on Thorntree. Hopefulist is an active poster that gave me great tips and she will probably weigh in here.

I traveled around Guatemala, though didn't make it to Rio Dulce or Livingston. Shuttles are very easily arranged and not expensive. I made reservations the day before and never ahead an issue, but didn't have a tight itinerary. The boat trip around Lake Atitlan can be booked simply by walking to a dock and getting on the next boat bound for whatever town you want to explore. There is no real reason IMHO, to spend one second longer in Guate City than you need to. No tour is necessary as there is nothing anyone has ever said to indicate anything interesting. Fly in, transfer to Tikal ( or take an overnight bus) hire Roxy Ortiz to guide you in Tikal, take a bus to Antigua (or fly back to GC and take an immediate shuttle to Antigua) and go to the lake from there.

Have fun. Any way you do it, you'll be sure to have a wonderful trip.

Thanks for the shout out, Lynne.

Gary -
You could do the same/similar itinerary for less if you do it yourself; the planning is part of the fun for me so I've never been tempted to hire someone else to do it. As above, share shuttles are easy to arrange. Here are 2 agencies with bilingual reps I've had good luck with if you want to arrange transport - private or shared - in advance:
www.adrenalinatours.com
www.rainbowtravelcenter.com

They could also book an overnight Tikal package for you, but do consider hiring archaeologist/naturalist Roxy Ortiz for tours in the north - she's amazing (don't do this through a hotel - contact her directly).
www.tikalroxy.blogspot.com

With 11 nights I wouldn't try to put in so many stops. Since it takes 2 nights to = 1 day to explore, you don't want to be averaging less than 3 stops per place; imo that would make it seem like half of your days were transition days (can take surprisingly long and be surprisingly tiring) and half "good" days. I'd leave out the Rio Dulce/Livingston/Puerto part at least and maybe save Copán for another trip - it's worth at least 3 nights imo.

Loads of photos with blog and detailed travelogue below. Happy planning!
http://www.flickr.com/photos/staceyholeman/collections

I agree with the two replies.Go nowhere near Guate City. Antigua is lovely as is Lake Atitlan. Every street corner in every city has a travel agent where you can buy transportation. If you have time you could read the second part of my trip report where I travel by bus in Guatemala. I am going back this New Year to see the Caribbean side and Tikal, and so look forward to your own notes when you return
http://andrewchum.blogspot.co.uk/

I think the price for the tour is reasonable considering all that is included, but I agree you can do it cheaper on your own. It depends on whether you have the desire and time to do the research. Also whether you feel comfortable traveling through a Spanish-speaking country on your own.

I went to Guatemala and Honduras in March, and planned the trip independently. I went to Antigua, Lake Atitlan with a trip to Chichi market, and Copan. However, I speak intermediate level Spanish and would not have been able to navigate as easily if I didn't speak the language.

Not saying you have to speak Spanish to travel in Central America--many travelers don't. However, I encountered several situations where there were no English speakers (cafes in Panajachel, some of the hotel staff in Antigua, staff at Copan hotel, gate staff at Guatamala city airport, shuttle driver, etc). If you feel comfortable with that, and like planning trips, then by all means go for it.

If you decide to do it yourself, here are some things I did and places I stayed you may find useful:

Casa Cristina in Antigua: http://www.casa-cristina.com/
TA review: http://goo.gl/g3Wnd
Posada Juma Ocag in Antigua: http://goo.gl/unA7X
La Posada de Belssy in Copan: http://www.laposadadebelssy.com/rooms
Copan Ruins: http://es.copanhonduras.org/
Mario's Rooms in Panajachel: http://goo.gl/205XO
La Posada de los Volcanes in Pana: http://www.posadadelosvolcanes.com/index.php
Macaw Bird Park in Copan: http://www.macawmountain.com/
Pacaya Volcano: http://goo.gl/znfyt
Casa Santo Domingo: Beautiful 5-star hotel. Didn't stay here, but toured the grounds, and took the free shuttle uphill to the restaurant for lunch (not the on-site restaurant which is expensive). Lunch was only $15. https://www.casasantodomingo.com.gt/en/

I would base myself in Antigua, and not stay overnight in Guatemala City (GC). When you walk out of the airport in GC, there will be shuttle vans that will take you straight to your hotel in Antigua for $10--no need to book in advance. It usually takes 45-60 minutes, but can take longer depending on traffic.

Antigua to Copan took about 5-1/2 hours by shuttle van and cost $15-$20. Much more comfortable are Hedman Alas buses. Antigua to Copan is $41: https://www.hedmanalas.com/tarifashedman.html I also took a shuttle from Antigua to Pana for $12.

Another shout out to hopefulist. She is very knowledgeable and you can trust any advice she gives you.

Whether you take a tour or do it independently, have a great trip!