Large single crystals of KTiOPO4 (KTP) isomorphs RbTiOAsO4 (RTA), CsTiOAsO4 (CTA) and RbxCs1-xTiOAsO4 (RCTA), x = 0.93, have been grown using the top seeded solution growth technique in a temperature controlled four-zone furnace. The seed was situated at the top end of the crystal, which minimized the part of the crystal that is strongly affected by the seed. The combination of Rb and Cs in RCTA is more favorable for crystal growth, in comparison with the end members RTA and CTA. Mixed crystals are Rb-enriched and contain only 20-30% of the Cs content of the flux composition. The IR transmission is slightly higher for CTA than for RTA. Various etching solutions have been used to study the domain patterns revealing that these crystals grown above the transition temperature consist of a few large domains.