To be honest, fixture congestion is something which really bugs me. Players can't physically be expected to play 22 league games + 6 Heineken Cup + 10 internationals so something has to give if we want the best on the field every week. If a Pro 12 team makes it to every final, they can play 33 games. This season Ospreys are playing Leinster 4 times. There's also the possibility that they'd meet a 5th time in the Pro 12 knockouts. Had things happened differently, they may even have met a 6th time this season in the Heineken Cup knockouts. That's 6/33 games or 18% of fixtures potentially against the one opponent which is ridiculous! The maximum amount of times a teams should meet in a season is 3 in my opinion.
If we are to keep the current situation of 3 leagues and Europe in place I think a 14 game Pro 12 + playoffs with 4,6 or 8 teams is a good option to pursue (my preferred option is a Euroleague as stated previously). Leave the B&I Cup (which I'd get rid of if there was a Euroleague), Welsh Premiership and AIL for player development if there was a shortened Pro 12.
There are only two ways to achieve the goal of cutting down the number of games played by players
1. a shorter season with less league games.
2. larger squads with more rotation
Mathematically, there are no other options.
For starters, the six nations should get together and completely re-arrange the calendar. Start with the National Leagues (The Aviva Premiership, the RFU Championship, Top14, Pro12, Pro D2 etc) then follow that with the Six Nations Championship on five consecutive weekends, then the European Championships on nine consecutive weekends. The majority of National Leagues players will get some rest & recovery time during the playoff phases, some will be able to get additional rest during the Six Nations. Those that don't will either have to be rested in the first few weeks of the ERC, or a three week gap has to be placed between the 6N and the ERC.
Next, the number of games played in the National Leagues needs to be cut dramatically, from the current 22/26 + playoffs to around 15/16 plus playoffs. This will mean a ditching of the tradition of playing home and away ties in the National Leagues. Have each team play each other once, and rotate the home/away fixtures on a bi-seasonal basis. An expansion of the leagues to 16 teams may be necessary, or some sort of two-tier pool system may have to be used.
The only downfall is money. How do you get the same amount of money for less actual games. One way it to hike ticket prices. You sell the idea on the basis that less is actually more. Less games will directly translate to less injuries for players, to more participation of the best players and therefore, to higher quality matches and a better quality product. I don't know about the forum guys here, but I'd sooner pay $150 to watch the All Blacks play South Africa once, than pay $50 per game to watch them play Italy three times. Also, less games will mean fans will have less opportunities to go to games. Currently, the season drags on seemingly forever, so fans can go any old time they like for 75% of the year. Cut down the opportunities and more people will take what opportunities there are. Its
one of the reasons why NFL plays to packed stadiums of 60,000 - 90,000 plus; because its only on for less than half the year. After the Superbowl in February, there is a "football drought" until the following August when pre-season starts.