I'm also considering a 5.4m van as we are rapidly outgrowing the Cali with two kids getting bigger by the day, the 5.4 applies for two reasons to me, you can just about park it in a standard supermarket space (not that i have requirement for a daily) and it gives extra payload over a 6m van, as the poptop is a must it really affects the stuff you can bring (and we seem to have a lot of stuff for the four of us).
would love a Westfalia Columbus 540 but can't justify the £100k price tag, been looking at the lower end Hymer group options, Sunlight Cliff or Carado CV Pro, okay they aren't as good as the Westy, but cover 90+% for 70% of the price, also looked at a Globecar Summit Shine at the weekend, really liked it, but closer to 85k so midway option, the Carado is £72k before discounts etc... so just weighing up options