I see the OP was made in 2014, but I'll respond anyway with my thoughts since it has been resurrected.
Started elk hunting in 1982 and have missed only one year since. Have taken my share of elk (14 since 2000) and all but maybe one or two could have been taken with a .308 Win, 7mm-08 or .260 Rem. Most could have been taken with my .257 Roberts, as only four that I can think of were taken past 350 yards. More than a few could have been taken with my .30-30 or even my .44 Mag carbine.
Started out with a 7mm RM and 160g bullets, which worked flawlessly for 20+ years. Took my last elk in 2015 with my buddy's 7mm RM and the same load I used for all those years. Daughter started elk hunting 3 years ago using a .308 Win and a 130g TTSX @ 3045fps. She has used this on antelope out to 350 yards and I wasn't worried that it would work on elk given her self-imposed limits on range (400 yards).
This year I bought her a .270 Win and worked up a 150g Nosler ABLR at 2912fps. If a .30-30 is good to 100 yards, the .270 is good to 700 (at 7000 feet altitude), retaining over 2100fps and almost 1500fpe at that range.
While my .338WM is very effective on elk, my 7mm RM has dropped them just as fast. A more powerful cartridge will rarely help in the event of poor placement. Penetration is important so I prefer monos, bonded and other premium construction methods. TTSX/LRX, AB/ABLR, Scirocco II and A-Frame are my favorites. Partitions work great, although I've never used them myself. Ditto Trophy Bonded, Trophy Bonded Tip and Edge TLR from Federal. That said a SIL took his first elk with a 180g Winchester Power Point at 382 yards. It was on the ground before we could see though the mirage caused by muzzle blast.
Over the years I've seen grown men blast away at elk, missing them entirely in some cases, wounding multiple in others. One thing they had in common was they couldn't shoot the rifle they had in hand.
I've seem more elk wounded and lost by people using a .243 Win that probably all other cartridges put together. The idea that it is a good choice for young elk hunters is at odds with my belief it is better in the hands of experienced hunters.
I've also seen what a girl 12 years old can do with a .25-06 ad a 117g cup-and-core bullet. Trophy mulie buck, trophy bull elk and a cow, all in one hunt. All one shot affairs. Her dad said the bull dropped faster than any he had seen.
While I've hunted elk with a .30-30, .375 Win, .44 Mag (rifle and pistol) and .45-70, I did so knowing they limited the range at which I could/would shoot. My .257 Roberts with a 120g A-Frame is good out to at least 350 yards (at 7000 feet altitude), other cartridges i shoot are good well past my limit of 600 yards.
The thing new hunters need to ask when choosing a cartridge are:
1. What is my tolerance to recoil?
2. How heavy a rifle/scope/ammo combo can I carry all day?
3. What is the maximum range at which I am willing to shoot?
4. What is the minimum legal cartridge, if any?
5. What is the performance envelope for the ammo of choice?
6. What is the experience of others with a given cartridge and bullet selection?
Numbers 1 and 2 are related, as rifle weight affects recoil. Number 3 should be based on the range at which the person actually practices and the point blank range for a given cartridge and zero. Number 4 may be based on bullet diameter, energy, or other factors. For number 5 I use retained values of 2000fps and 1500fpe as rule of thumb minimums for elk. This helps ensure reliable bullet expansion and penetration. Some bullets (monos in particular) may perform better with higher impact velocities. Number 6 may not be answerable. Recoil and ballistic calculators are your friends.
Once those questions are answered an informed cartridge decision can be made. What is best for one person my be a horrible choice for others.
All that said, I'd be happy with a wide variety of cartridge and bullet combinations. Placement trumps cartridge. For a noobie I prefer a minimum of something like the 6.5 Creedmoor and a maximum of a .30-06. That includes 7mm-08, .270 Win, .280 Rem, 7mm RM, and.308 Win. One thing I tell people making the election is to compare ammo costs - I recommend they practice until they are expert with their rifle and cartridge of choice.
My sons-in-law got .30-06 rifles for wedding presents.