I don't think your problem is small bowl, but more like the low performance of the Iolite. Iolite can hold quite a bit of herbs, but doesn't vape efficiently as convection vapes and it takes almost 20 mins to cook a bowl.
The Cloud's bowl is only slightly larger, but it can powerfully extract the bowl in few hits making huge blasting vapor clouds. And that makes everyone blazed. Big bowl are more like problematic in vapes as they don't work well with small personal loads so it will urge you to fill it too much. Also more than start-stop feature you just need convection heat, that works just like this. When you stop pulling herbs cool down. All units I list are convection as I think that's what you want.
My advice is to save money, because really good desktop units are not cheap.
VXC:
-Direct draw vape, you load vape, put on glass hydratube for water filtration and inhale as you wish.
-All glass - plus is the taste, minus fragility
-Powerful convection, no need for stirring.
-It can load probably slighty more than Iolite, but it's vapor is very satisfying.
-Can deal with small loads too.
-Glass heat exchanger. Can last looong, but also you can break it in second.
-Inconsistently in stock, pricy (450-550$), but it's probably the most luxury and satisfying desktop today.
SSV (DBV, LSV):
-Probably the best whip vape. Quite large bowl, i think it can hold a gram.
-If you load it enough it makes satisfying clouds, it needs a lot of stirring.
-This is that vape that urges you to load it more than you need.
-200-350$
EQ:
-Very versatile. Default dual-mode, but can be easily used in even more ways.
-Not much well designed glass. Needs a lot of stirring and prepare for some minor trouble with airpath.
-In my experience it can last long time. MY EQ was heavily modded and abused and used in exotic ways and is still like new. If the glass breaks it's cheaply replaceable.
-Similar heater design as SSV,DBV,LSV. Ceramic heater in glass before herbs - so heat is mostly at the center of airpath and you need to stir a lot.
-Cheap (200-250$)
Volcano:
-It can hold a lot. A LOT. I think 2-3 grams possible.
-Almost indestructible solid design.
-Profesional bag filler, great for parties. Not so great for personal use as it really urges you to load too much.
-Huge, loud and expensive (500-600$)
UD:
-Well, you said you want huge bowls, this is the opposite, but you can cycle several tiny bowl in very short time.
-You must let it warm up for like 30 minutes, but then it's ready for 24/7 usage.
-When warmed up, you can easily load a stem, connect it, cook in in few pulls and easily unload. Or reload if you want more.
-These log vapes have tiny bowl that you can cook very fast and effectively. So you can dose very precisely and not waste anything.
-Great for personal use.
-Beautiful artistic finish.
-150-250$