Has anyone mentioned the 55-300mm? It is rumoured to be better than my old 80-320mm, admittedly for twice the price, but you can buy them 'unboxed'.
Anyway these are my 80-320 aircraft efforts on my K-M, I have yet to visit a full blown airshow with it but the Shawbury trainees do get close sometimes, (& if the 55-300 is better, then - - - )sorry to anyone who has seen these before.

http://www.flickr.com/photos/28204187@N08/sets/72157619450555912/

I tend to use my 28mm Takumar-A f2.8 more than the Pentax-A 50 mm f1.7 - why? because at 42mm equivalent I can fit more in - Its surprisingly good for contrast & sharpness considering its the 'budget' lens.

Indoors example:
http://www.flickr.com/photos/28204187@N08/3766920072/in/set-72157622515123575/

I have used both the Fuji & Ilford scanning service - but not since I bought the K-M in 2009!
All I can add to the discussion is that when Fuji 'switched' to a new lab in 2008 the quality was greatly improved.
This is a resized image I uploaded to Flickr:
http://www.flickr.com/photos/28204187@N08/4283954969/in/set-72157623109209463/

I believe its FUJI Provia400

I wish I had known about Jessops - on our way to the British Museum last weekend we came across a Jacobs & a Jessops opposite each other - didn't bother with Jessops but Jacobs did not have much Pentax either!
As an aside the wife insisted I did not take the DSLR with me so I only had the little old FUJI in my pocket, only to discover that the British Museum is the one with the 'new' attrium & you can take photos in side (i pressume no flash).
Hopefully I could have done a little more with the K-M:
link

You could also try the exposure bracketing facility - depends on the space you have on your memory card!
Like John suggests I have been experimenting with the Exposure Compensation control - I used to be wary of adding more/less than + 0.3 or - 0.3 ev, not any more.

I tend to shoot 'best' quality jpegs, then carry out any minor adjustments in MS PictureManager. On my recent trip to Amsterdam I discoverd I was somehow leaning to the left when I took my shots - canal water does not flow downhill, so had to adjust the rotation of hundreds of pics - the computer could not have coped if they had all been raw! I finished the 'project' by renaming, & sorting (by time taken) the files from 3 camera's (almost 1000) in Adobe Album Starter.
Regarding highlights, Pentaxs underexpose anyway to protect them.

I was on the brink of buying a PK fit Bell & Howell (think Mamiya 35mm) 60-260 macro lens for £20 recently - boxed in original bubble wrap with instruction manaual - went to the bank to get some cash & on return it had gone!
Think I am cured for now, Lol.

Aren't Tokina owned by Hoya, & don't some recent Pentax lenses share specs with recent Tokina lenses?
One way to sell Pentax stuff to Canikon people.

As an aside one of our local charity shops was selling a HOYA lens a few weeks ago!

When I bought my K-M I already had a manual focus Pentax 75-150, but needed more reach on a budget - ended up with a used 80-320mm from SRS with a small waranty - it cost £120 & is still working ok after a year & half ownership. Results are surprisingly good (& it works on my 35mm film Pentax), from 80 to 200mm its quite sharp & contrasty - though I understand the 55-300 digital is better overall but for a lot more cash at the time (55-300's can be bought unboxed now).
Some 80-320's can have problems with their aperture rings plus beware of fungus.

Some of my 80-320 samples: (I am a DSLR learner too so no expert)!
http://www.flickr.com/photos/28204187@N08/sets/72157622639681232/

We had a power cut last night - managed to take this with my 50mm f1.7!
;

http://www.flickr.com/photos/28204187@N08/5190624760/in/photostream/