Ok, where to start.
I was just looking at the runtimes on the HDS site: for your use a rotary may be ideal(very easy to adjust 24 levels to your desire)Otherwise a clicky would be fine as well and i hear the rotary can be configured to be a clicky if desired.
123 primary gives 1.5hrs on max(lvl 24)/2,25 hrs on lvl23, and lvl 22 gives 3.25hrs. There is not a big difference between lv 23 and 24and most likely you will not always be using max, so you can get the runtimes you're looking for on primaries. 18650 provides very good runtimes.
approx runtime chart can be found here:
http://www.hdssystems.com/Content/LightFaq/#LevelRuntimes
If you are intersted in HDS, they can be found in the FS section quite frequently lately but go very quick. If you want the flood version there is one in the FS section for a good price (you could at least contact the seller to ask your quesions of concern on flood)
Elzetta gives you a few options you'd probably want the bravo(I do not know much about the alpha but have heard mixed opinions)
With the bravo they use 16mm cells, but you can get the bored bravo from Oveready that allows for 18mm cells. The bored bravo will not accept all protected cells. I know they will not accept keeppower, panasonic or lg protected cells. I have a bored bravo and bored it out myself even more to accept any 18mm cell.
With the bravo you can use an M60/61 drop-in that is in the 300lm range or you can get their AVS head which will give you up to 600lm depending on if you use 2x123, 2x18350(unprotected) or an 18650/16650. The bravo is slightly shorter than a Malkoff MD2 or MDC 16650: I'll just post a pic of these lights so you can get a size reference.
Malkoff MD with M61(N) is a good option in the 300lm range for good runtime. I am not sure what M61HOT MD2 or M61T MD2 would provide for runtime but are both really good cool white lights
as mentioned the MDC 16650 is a great light especially if smaller size if wanted. It has l-m-h settings/ 20-100-500lm on Neutral version(CW would probably be a bit higher) This light probably has one of my favorite tints of all my malkoff devices and in the top for favorite tint overall of all my lights
If you want to lean towards great quality chinese manufactured lights, then Fenix or Eagtac would be my suggestion. I like the quality of Fenix better but Eagtac has beter options for emitters.
Then you also have Zebralight which make great lights in compact sizes. I have a sc600 MK3 HI and did a recent runtime test on sony vtc6, panny GA, and LG MJ11. on max setting (1126lm) I got 2.25hrs on the ga cell and 2.5hrs on the MJ11 cell. If you were to use the lower settings of 5xxlm or the 3xxlm settings, I'm sure you would get quite a bit more runtime. This is a 18650 light but it is about the same height as the HDS rotary 123 or the Malkoff MDC w/vme head on 123 body(you'll see in pic)
They also have single 123 lights but not sure of runtime
Now for a few runtime test results(didn't have as much as I thought for the smaller lights)
MDC 16650 500lm Keeppower 16650 2500mah: 1.5 hrs of full output, then gradual decline in output. Total runtime of 2.75hrs (can't recall ending output or if it cut off)
MDC 16650 head 500lm on 123 body: Keeppower 16340/AW IMR123: 30-35min of full/55-1hr till cut off. Not ideal for your use
Malkoff MD2 w/M61N 300lm: Protected GA 3500mah cell: Currently retesting: Initial results: 3-3.5 hrs full output then gradual decline. @4.75hrs approx 100lm output, @5.75hrs approx 50lm, @6.5hrs and end of test(had to go to bed) 20lm
MD2 w/M361N 375lm: Protected GA 3500mah cell: 2.25hrs till gradual decline, 3hrs 49min light cut off and was only producing approx 20lm
Bravo w/M361 219B: Protected GA 3500mah cell: 2.25hrs full output and starting gradual drop off, 2hrs 55mins light cut off approx 20lm
Will post a couple pics after dinner. Hope this info may help and these are the only lights I really have experience with