We just completed our first back-to-back cruise on the Sun Princess, 12/29 to 1/8 and 1/8 to 1/18, something we've always wanted to do. We're "Elite" category members, having sailed Princess over 20 times, usually 10 days minimum but quite often it's 14-16 day trip (Panama Canal several times). We wondered if 20 days would be a bit long, but it wasn't.
Our only eagerness to have it end was due to the weather and sea conditions. Of the 20 days, 15 of them had gale-force winds and extremely rough seas 15 ft swells and waves. It just got old bouncing around so much, to the point that our sleep was also disturbed each night. Instead of the nice sway and lull to sleep (I always sleep so well onboard!), it frequently felt like we were going to fall out of bed and we'd jolt awake. So sleep was a challenge along with all the other rocky sea challenges during the day.
Just a weather-related challenge, not ship or length of cruise.
We've sailed Regal also, a 15-day Panama voyage in Jan 2004. We prefer the size of the Regal and Sun/Dawn, as we felt the Sapphire ship in Nov 2004 was way too big...for our preferences. The Regal is a great ship, but the design is odd in places, we think. For example, the huge casino occupies some prime real estate at the top forward deck....which could be a perfect deck observation location, but the windows on the casino are all tinted and there's zero visability through them. Seemed like an odd spot for a casino and a strange usage of space.
We enjoy searching out a quiet "nook" for deck sunning, reading and relaxation, and there are very few on the Regal, other than the usual Riviera or Lido deck areas with all the other passengers around the pool. We just enjoy the other Princess deck plans where one can find that quiet lounge chair in the sun. Hard to find on the Regal.
Locating the dining rooms on the Regal can be interesting! You can't get to either one (on two separate decks) without going down an elevator, walk across the deck, and then back up the elevator.....there's no through passage on either deck. Some passengers found that very difficult.
Our cabin was on Aloha Deck aft, an outside veranda. The cabins are tight but adequate, and after 15-plus days, we were eager for some "elbow room". Not a bad situation, believe me because hey, we're on a cruise for 15-plus days!! :-) But spreading our wings upon return home did feel nice.
Would we do 20 days again? Absolutely, but we'd be selective on the ship, cabin location. Would we sail Regal again? Sure, but we didn't care for the lounge chair deck layout...for our preferences.
Happy cruising! You'll enjoy taking a longer cruise, I'm sure. We sure do!