I've played approximately 10 games to completion (or at least to the point where everyone quits) and I've noticed a repeating pattern. To generalize, players are stockpiling units as a one to two hour leadin to the final "coup de gras" battle. Once that battle is over, the losers usually resign. I see this not only as poor strategy, but also a monumental wasting of time. Furthermore, the player who loses the battle, will often retaliate by explaining how over-powered or unbalanced the winners units are and so on.
Not poor strategy but just strategy actually. If you read Clausewitz's Vom Krieg he explains why but to give a quick summary: Decisive victories are always sought after. As for the last line, yeah that's true of any RTS but there is always imba it's a matter of how much.
But, now for the honest reply to your question.
Speaking of that, has anyone had luck doing anything but trying to blow up only capitals in a large scale engagement?
Yes, target the smaller vessels to reduce DPS dramatically and also by the time you lose a cap ship you should have taken down cost at the very least equal to or greater than your cap ship plus whatever else is counted for experience up to level four. A loss of a capital ship at level 5+ is unacceptable however. This game is a numbers game generally. That being said, why the hell would you have flak ships targetting the cap ship when they do nearly zero DPS against capital armor, they're better directed vs fighters and LRM.
Your fleet should be targeting and exploiting things with the greatest weakness versus the damage. Hence, your bombers will be focusing on capitals while your fighters will be focusing on light armored frigates. Your main line be it the LRMs or whatever else can either focus fire the support or their cap ship depending on YOUR GOAL. You can either try to DPS race down their cap ship or kill some of their units and pull out before they down yours in which case you have a slightly damaged cap ship with loss of anti matter due to hyper spacing and they have lost actual materials.
Economic warfare is very hard to pull off and is usually done in FFAs by manipulating the market and even with raiding against economic centers it is not going to ensure a decisive victory which may mean that they will do the same thing to you and it becomes a boring battle of attrition. If you can manage to split your armada then you can try this but the opponent will either be chasing you or doing the same thing , if you're going onto their home turf expect to be thoroughly lashed if they have phase jump inhibitors. In the end, it's just a very complex strategy to execute with very little rewards as opposed to smashing someone head on. As I mentioned before, econ screwing is best done in a FFA but not in a 1v1 not in a team game due to the resilience of the structures and the need to have a balanced fleet/large fleet/reactionary fleet.
Is it pertinent to take the feet out from underneath someone as an alternative to beating them toe-to-toe.
A single loss of an LRM would also mean you would at least need to take out one metal extractor and the loss of a few would mean you would have to take out at least a refinery or a trade center, it takes awhile even with 20 ships to take down a structure by which time the opponent can react or has done something else to extract an equal price from your hide. It is always better to destroy the enemy fleet head to head simply because it ACHIEVES A DECISIVE VICTORY . Unless... it's early on say before the 20 minute mark.
With the current lay out of the game, it's better to clash toe to toe, if they cheapened siege vessels then it might be arguable to run a secondary fleet of siegers to destroy an enemy planet. Problem is that regardless it eats from your standing fleet which means when it comes time to fight that decisive armada battle you will have lost some advantage. Before in the beta system where fleet size was governed by planets, it could've been arguable for it to be a strategy of a certain type.
That being said, the opponent should almost always know where you are and vice versa due to extensive scouting which makes parting your fleet a painful thing. As the one initiating a divided attack, you are allocating resources first which enables the opponent to calculate how much he or she needs to fan out to either counter or take more. In either case, you are at a slight disadvantage despite having the initiative.