Estimate the asymptotic efficiency of a rocket?

Question

Estimate the asymptotic efficiency of a rocket (or other launch vehicle - Saturn V, Delta, Ariane, Space Shuttle, whatever). A rough estimate would be ok.

As in: what proportion of the total chemical energy in the fuel at launch is ultimately converted into gravitational potential energy + kinetic energy of the launch vehicle/payload?
(To get that PE I expect you integrate Newton's Law of Gravitation, from ground to final altitude, using only the mass of the payload. To get the KE you need to know the final velocity components - is that radial and tangential to the earth orbit?)

For a bonus, what was the single biggest cause of inefficiency, and can you quantify it? (I think it is lifting your own fuel, followed by air resistance)

(I don't just mean the engine efficiency of the engine, I mean the whole deal.)

(Not sure where to put it - this question is a little chemistry, a little physics and a little astronomy)

C'mon people!

You can find some useful information, including parameters for the Space Shuttle here:
http://fti.neep.wisc.edu/~jfs/neep602.lecture29.chemRkt.96.html

and for Saturn V here:
http://ocw.mit.edu/NR/rdonlyres/Physics/8-01Physics-IFall1999/0FDE03A1-2828-402F-B6E5-4844E963BE18/0/assign6.pdf

and on mechanics, orbits and more parameters of launch vehicles here:
http://www2.jpl.nasa.gov/basics/bsf5-1.html

Answer 1

Just a back of enveloppe calculation.... 2%.

Suppose we lift 1000 kg payload to a circular orbit of 300 km and v = 7.8 km/s. The mass ratio (mass fuel/payload) is taken as 16, which is the number for the space shuttle.

1) Kinetic energy = 0.5 m_payload v^2 = 3x10^10 Joule
Potential energy = G m_payload m_earth (1/R_orbit - 1/R_earth) = 3x10^9 J
Total final energy 3.3 x 0^10 Joule

2) Mass ratio = 16 therefore 16000 kg fuel. Assume LH2/LO2, heat of combustion 100 MJ/kg. Total energy 1.6 x 10^12 Joule

3) Efficiency 3.3 x 0^10 / 1.6 x 10^12 = 2%